You're kidding me.
4. Puts other important foreign policy options at risk (Iran, Syria, nuclear cooperation)
5. Will result in an insurgency in Crimea, which either the Ukrainians or the West will have to put down
6. Will require attacking targets in Russia, and consequently will lead to an escalation, despite your attempts to make Putin out as a bitchmade Russian Hitler who will just go "Oh I'm sorry let me remove those Russian corpses so NATO can roll in right beside my capital."
7. Will have notable civilian and military casualties;
8. The Ukraine is not strategically valuable to the US. Maybe to the EU. Maybe to Russia. But not to the US. This is something for the Europeans to handle if they think it's important... And if we accept your arguments re: Russia's willingness to fight, it'll be no big thing.
As for the EU argument, I'd say that for the most part, success that can be attributed to the EU is somewhat elusive. The countries that are doing well were already doing well. The countries that are not doing well are that way for the same reasons they weren't doing well before the EU. Not that it matters.
You know what I just realized?
Your PCFs new Peter Dow.