How would the soviets have eliminated the superior E-3 sentry and NATO's C2 structure?
The fighting in the air over Germany would probably require two E-3s airborne at any one time, so eight would be required to maintain comprehensive 24/7 coverage. NATO began receiving their 20 in 1982, but I don't know how many they would have had in 1985. Even if they are all destroyed in the opening Soviet strikes (incredibly unlikely), the US Air Force had their own fleet based in the US that would be deployed as replacements and likely based in western France or Britain (almost impossible to get at). Soviet weakness in PGMs means that their impact on NATO's well-dispersed C2 infrastructure would be relatively minimal. I don't want to downplay the Soviet threat here, but the NATO C2 net was far more flexible than the Soviet one, and the Soviets were far less able to strike at NATO's C2 net than vice versa.
Would there have been a way to eliminate the airfields key to NATO's defensive strategy?
Given three days of warning, NATO aircraft would be dispersed enough to keep this from happening at most sites. Airfields would certainly be hit but maintenance equipment (though not personnel) is generally replaceable. An attack with literally zero warning would have a good chance, but even a few hours of warning would get a lot of planes in the air.
Could the Su-25 engage Nato ground units with effect?
The Su-25 is a fairly generalized CAS aircraft compared to the A-10. Most importantly, it lacks the A-10's battlefield standoff range, which allowed the A-10 to engage and destroy enemy tanks from beyond the range of dense Soviet MANPADS and SPAAG fire (engage from 2,000 m to 1,500 m and then turn away before coming within 1,000 m). Even with rockets, the Su-25 would have to get really close, so I doubt it would be as survivable as the A-10. Of course, the entire A-10 fleet was only expected to last through seven days of fighting (420 planes losing 60 per day).
Would Nato aircraft survive the amount of SAMs and AAA the reds brought to bear?
In a word, yes. The Soviet SAM belts would put huge limitations on the freedom of movement of both NATO and WarPac aircraft because the Soviets had to deploy their SAMs inside free-fire zones while NATO SAMs were better (not perfect) at IFF. However, NATO pilots had been used to treetop-level penetration flying for a decade, so they were definitely aware of the threat.
Would air superiority shift between air forces or would one dominate the other?
Over West Germany, the Soviets would be able to achieve, at most, localized and temporary air superiority in support of ground attacks. Their method for air-control relied primarily on deploying long-range SAMs close to the front, which was effectively an admission that their aircraft did not compete well with NATO aircraft (not that it makes it a bad tactic, SAMs are just less effective than other aircraft at air control). Eventually (I don't know how long), the odds of NATO achieving air superiority over East Germany was higher than the Soviets achieving air superiority over West Germany.
Could reforger occur quickly enough to prevent allied units from disengaging due to lack of supplies?
The purpose of REFORGER was to deploy several divisions of American and Canadian soldiers to Germany to meet up with their equipment and move to the front within days. This was a separate effort from the necessary transatlantic supply convoys. The answer to the logistics question depends on how long the war takes; a Seven Days to the Rhine scenario (I know it's a nuclear plan) would mean that the Soviets either win or are stopped before any convoys would even leave, and a Red Storm Rising scenario with a war lasting about four months is very different. It would probably take about a week (from the war warning three days before the fighting starts) to get some ships loaded up and on the way across the Atlantic. Of course, they wouldn't arrive until the third week after the war starts. Before then, transatlantic support would require an airlift like Operation Nickel Grass, utilizing Air Force and CRAF aircraft. This would probably be moving something on the order of 10,000 tons per week across the Atlantic; I don't know what kind of impact that would have on the situation.
What is the soviets neutralized the sosus line with a guided non nuclear missile strike from a submarine?
The ground stations at places like Keflavik would certainly be vulnerable, but I don't think (just my speculation) that there wouldn't be more defensible back ups in place or ready to be installed. Of course, there's no way the Soviets are getting at the sensor network, so the ground stations would be the only vulnerability.
Or a red storm rising like operation to capture and utilize iceland to strike NATO convoys?
I would consider this possible but extraordinarily unlikely. Soviet airborne forces would already be stretched thin by requirements in Central Europe, and stopping the NATO convoys only becomes a problem in the second and third weeks of the war, well after the Soviets thought their window for winning would be over. As for basing bombers there, its far too vulnerable and they can already reach the shipping lanes from far safer bases on the Kola Peninsula.
Would the VDV have dropped beyond enemy lines to destroy enemy installations (presypply depos, communications stations, C2 structures) and cause chaos in Natos rear so that Nato is forces to fight on two fronts?
The Soviets had something like ten division equivalents of airborne (planes) and air assault (helicopters) troops. However, with three days of warning and the capability of NATO air defenses, I doubt the Soviets would be able to deploy that entire force into the NATO rear areas. However, the ability of the Soviets to move huge numbers of airmobile troops by helicopter into the rear of the FEBA (within a few kilometers of the front) should not be underestimated. I would consider the chance of the Soviets taking and developing an airhead to be minimal if there are E-3s in the air when they try, and Northern Germany and Denmark would be the best location for that. It would be important for the Soviets to take and control the Danish straits and the Baltic coast, using both VDV and naval infantry. The attacks against logistics and C3 stations would be carried out by GRU Spetsnaz, while VDV Spetsnaz would be used to take crossroads and bridges (and the like) behind NATO lines. My personal opinion is that the GRU Spetsnaz attacks would be harder to stop and more damaging than the Soviet air strikes, but would likely be limited to the first few hours of the war before they get mostly cleaned up.
How would initial plans change as the battles occur with air support on both sides coming into play?
Not sure what you mean here. The plans were made to include air support. NATO's reliance on air power was heavier than the Soviets because NATO's biggest advantages were in the air. As we saw in Iraq and Yugoslavia, the ability of aircraft to interdict against ground targets is generally overblown, but NATO CAS capabilities were not (as much?). Of course, the Soviet C3 network has to be transmitting to be working, so the transmitters can be found and destroyed. The Serbs didn't have to worry about that because they weren't fighting a ground war against NATO at the same time.
Would the soviets abandon the big push for multiple fronts stretching Nato to cover multiple threat axis'?
Only if the big offensive in Northern Germany doesn't work. Trying to fight into Central Germany and Bavaria is going to be a much more difficult prospect, especially because of the higher proportion of American units they would be facing. The schwerpunkt of the entire war is Germany, so extending to other fronts like Italy, Greece, or Turkey would probably be more distracting for the Soviets than for NATO.
Would NATO's plan of combined defense work or change ?
The plan for forward defense would probably collapse very quickly (within hours) when it becomes apparent that the Soviets are going for envelopments wherever they can. The forward defense was the official line but I think everybody (especially the Americans and British) was trying to prepare for a mobile war hinging more on mobility choke points (mountain passes and river crossings) than fighting for every single town. The Germans would probably be the most committed to the forward defense, but they would not be trying to fight to the last man for every terrain feature. The Germans would probably be the most vulnerable to being surrounded on the company or battalion level, but breaking out would be a highly variable thing.
Could they be overrun by the number of Soviet aggressors?
In the first days of the war, the Soviet offensive would be (trying to be) highly fluid, reinforcing success at NATO's weak points rather than trying to grind down every NATO position they come across. Unless NATO misses the deployment of huge numbers of top-line Soviet forces, GSFG's numerical advantage was not as high as you might think. They recognized the efficacy of flexibility over the difficulty of directing huge, preplanned assaults, and were trying to replicate NATO's fighting style as best they could.