To answer your questions about Ukraine:
Supply Ukraine with weapons and training on them immediately . Anti armour weapons, man packable anti aircraft missiles, personal weapons, tanks (leopards would be nice), APCs, etc etc. Yes I know significant training is needed on some but it can be expedited/sped up (I have military experience from when I was younger so I'm not naive). The concept of running a tank should be the same to any tank crew for example... it is just the specifics of each model. Worrying about Russia learning about them is silly. They likely know a whole lot about our stuff already.
Fire Germany's reactors back up so they can reduce or eliminate Russian natural gas. Heavy meaningful sanctions that will actually hurt Russians at home. You do understand qthat Russia wants Ukraine under its thumb after this don't you? What Putin wants will essentially be Russia on the Polish border. He was an agent in Germany. He dreams of owning the Baltic states, Czech, Slovakia, Hungary, Romania, Bulgaria, etc. again. And when he has them, the rest of Europe will be scratching their collective arses and saying, "Gee, how'd that happen?"
And quite frankly I'd love to see my government force natural gas pipelines to our coasts (and fast) so we can be an alternate supplier of natural gas to Europe. Fuck Putin and anyone in Russia who supports him.
These aren't security experts FFS. Personally I wouldn't stop my life over this, but it is good to understand what some of them have in mind, and keep an eye on it.
Remember these guys are predisposed to killing themselves for the cause. We have to watch for things like getting themselves infected and travelling somewhere before symptoms show. They could weaponize themselves. As an example, look at how Ebola went to Nigeria and now some student sneaking into Senegal. Imagine if it was a whole bunch of nuts doing it on purpose. It's not something to just dismiss. Even if it didn't kill thousands, the panic caused in the general population who thanks to modern news organizations have no ability to filter or prioritize what they need to panic over. And western nations are too politically correct or have too much economic interest to test people at the borders or airports.
I'm not going to get bent about the whole thing, we should have already guessed guys like this have been trying to dream up ideas for years. But it shouldn't be discounted out of hand.
3. We have antibiotics.
FTFY: We have antibiotics that we have rendered useless because we have fed them to cows to make them bigger which we then eat and so any germ we might encounter may already have evolved defences from said antibiotic.
FWIW, there are a lot of animals that can carry plague, not just rabbits (I know you implied that). But people don't know that most rodents in North America can carry it including squirrels, prairie dogs, rats, etc etc etc. And people still die from it occasionally.
With your bare hands?!?