Far more plausible that the Russians are preparing for war with NATO as a preventative measure “just in case.” Which, I would expect them to.
That doesn’t mean that they’re about to attack the Baltics or Poland, etc., Again, Putin and his advisors are obsessed with Ukraine in a way that they simply aren’t obsessed with other European countries.
Yes and no. Putin whines about the Russian minority populations in the Baltic states *a lot*.
It would be best for all parties involved if we could get the Baltic states to change their policies towards Russians, but it's not like Putin is doing much actual good for them. The very awful treatment of Baltic Russians is only going to worsen if Putin actually invades the Baltics and fails.
These are points American leadership ought to communicate to Putin if he even thinks of destabilizing things in Europe further through military action (outside of Ukraine, anyhow).