Your suggestions are far off from realpolitik. This is the recipe followed post-WW1, which brought us WW2. Europe itself is the proof that cooperation and good relationship among neighbours are the policies that bring peace and prosperity.
And Putin is not an idiot to attempt expansion to lands with no ethnic-russian population. Such thing is clearly not feasible without the power structures of the former USSR.
WW2 was brought by the humiliation and starvation of the German people by the European winners and by their own politicians, and Hitler easily capitalized on that making his rise to power a slam dunk.
People like to think that if they would have assassinated Hitler early on, WW2 wouldn't have happened, but that's wrong. That would have just left the power vacuum empty for someone else to capitalize on the German populations' grievances and start the war.
The history lesson is to make sure the masses of people are taken care of by their leaders, not to start censoring, imprisoning or assassinating political opponents who capitalize on the peoples' unhappiness.
And Putin is not an idiot to attempt expansion to lands with no ethnic-russian population. Such thing is clearly not feasible without the power structures of the former USSR.