It's like me telling my next door neighbor they can't be friends with another neighbor. It's none of my business, and I'd be an asshole for demanding it.
It also places Russia in direct violation of their own agreements. https://en.wikipedia.org/wiki/Budapest_Memorandum_on_Securit...
B) Ukraine isn't much closer to Moscow than Lithuania is (and hugely father away from Leningrad than Estonia is), so this seems irrelevant.
What your neighbours and their friends put on their lawns is none of your business. If it's a lot of stuff usable for defending against arsehole neighbours, maybe in stead of attacking them you should think about what kind of a neighbour you are.
It is not. Russia does not have any say in what alliances other nations choose to join -- apart from the "last argument of kings" of course, and what's scary to me is that there are so many people like you around that seem to have this Clausewitz idea of war being "politics by other means" even in the present day.
Your comment clearly makes excuses for Russia's actions, so no, in your case you are not keeping both of these thoughts in your head.
Would you be so quick to defend the United States in the same manner if they had expressed concerns about Mexico's foreign policies for the past ten years? Or an invasion of an alternate-reality Cuba with a democratically elected government tomorrow?