Gorbachev wanted to keep USSR intact. He didn't want a post-USSR Russia. He initiated referendums to that end. But USSR was already on the train to dissolution and nothing was going to stop it.
Indeed. He didn't weigh in on the current debacle but he praised Putin's seizure of Crimea.
He was a product of his upbringing and honestly he always seemed like a weak player to me -- but really I have no idea how difficult it might have been to bring off the reforms he did under Andropov, Chernenko and then his own premiership.
(It wasn’t exclusively in the USSR sphere of influence, but it was in their sphere of influence.)
That’s how the USA imported the Yugo!
And the GDR still got the best deal of all of the ones you mentioned. But there's massive inequality, massive unemployment. (And as a result, extremism, political fatigue, corruption, etc)
to be convincing you have to point out things that the transitioners could have done that would have worked better, but even the best experts in the world did not know any better than what was tried, so that's going to be a tough case to make.
That said, the former Soviet Republics that transitioned well are those that were smaller, already edging their way towards a market economy before the USSR collapse, and received substantial help from (and eventually joined) the EU (Baltics, Hungary, Poland, Czech Rep., Slovenia), and in the case of E.Germany, unification.
I don't think most of the others have fared that well. GDP/Capita is not a good measure because it doesn't take inequality into account.