With the extra German forces and supplies in SWA is there any change the Maritz rebellion gets greater support among the Boers? (to the point the South African government can't participate)??
Would actually cancelling a land portion of Gallipoli lead to another attempt at rushing the straits with the just navy which works this time? (the Turks got lucky with mine placement the first time)?
Would Spee's squadron, reinforced with a BC or two just stay in the Pacific islands and try to repulse an invasion of Rabaul or Samoa (or counter attack) vs fleeing across the Pacific?
For the Boer question, you need a person with better understanding of SA politics. I can give you a firm "maybe".
I personally don't think the forcing the straights was that close to working since there were additional minefield around the turn of land. And batteries that never fired. Plus some German warships that can come out and support the final set of minefields. We have spent a lot of threads on this battle.
As to a decision to try again, i would say 'unlikely but possible'. I spend a lot of time criticizing Churchill who I believe is the man most responsible for the death of the British Empire, but the naval operation was well worth the risk. The original orders should have been, "Force the straights or don't come back". Basically Kemal Pasha orders for the 57th Ottoman regiment, but for the BB squadron.
Sure Spee could do it, but they would have to have supplies such as coal and additional ammo. And things like food for the men. So either Rabaul has been setup as a base,or someone has organized a good line of freighters and colliers supplying them. It is not that it is hard, it just is a lot easier with prewar planning. As funny as it sounds, Spee TF need a supply TF following behind, hiding at anchorages, and the like. But if one say parked a collier and freighter with ammo/food at Rabaul. Another say hiding in Truck. Another say at Bikini atoll. Then Spee is a holy terror until sunk. Now what happens is the British BC are leading cruiser squadrons in the Pacific. Probably 2-3 of them. It would be the stuff of great movies for a century.
When we talk about these bases, I assume people understand these guns are defending warehouses and huge piles of coal. Think of how the USA carved fuel tanks into mountains at Pearl Harbor. Or for a failure, how Mac did not move the rice from warehouses in Manila to Bataan.