Too many questions.
1.Even if he succeeded would he be able to hold on to power, perhaps we'll see a very different civil war, reactionaries vs. reformists. Another possibility would be a situation where generals replace eachother by force.
2. If Kornilov would not concede to the Central Powers he'd probably be replaced. Russia had nothing to fight with anymore, and both soldiers and civilians were starving.
3. Part of the reformist movement against Kornilov??
4. Depend, really, there might still be a civil war and chaos.
5. Would Hitler arise to power without Communism and the red scare? No, nazism wouldn't be strong.
Would some kind of crazy nationalist take over Germany and start a new World War? Very possible.
6. Depend, given a big pension and a villa in the Crimea? Some of his relatives could be chosen as a figurehead, but Nicky's era was over.