Good questions, hard to answer. A few quick thoughts. I will try to dispassionately focus on the facts of the military situation as I understand them. That's going to be hard to do, but I'll try. I'm sure there are experts who know much more than I do.
> Does anyone have any projections for how this war will go? Is the Ukrainian military powerful?
There are many projections, though wars are notoriously hard to predict.
Ukraine has a military, but Russia is extremely powerful and has one of the largest militaries in the world. Source: https://worldpopulationreview.com/country-rankings/military-... Russia has tons of equipment & everything else it needs to overwhelm Ukraine.
Geography is a key issue in wars, and Ukraine's geography is awful for Ukraine in a Russia/Ukraine conflict. Again, here's my understanding. Ukraine is just a flat plain on the path from Russia, so geography provides relatively little protection to Ukraine. The Dnieper River (which runs basically North/South in the middle of Ukraine) does provide some geographic protection, but by that point Ukraine has lost a huge amount of its territory. Kyiv (the capital of Ukraine) is on the Dnieper river, but it's way to the north near Belarus, and thus Kyiv is relatively easy for Russia to reach via Belarus. The Carpathian mountains in the west and the Crimean mountains in the south make it harder for other countries to help Ukraine. The eastern part of Ukraine has a lot more Russians than the western part, so the eastern parts will be easier for Russia to hold since they'll get more help from the population.
One discussion of a plausible outcome is here:
https://www.youtube.com/watch?v=Z9c_HhpvBpg
(Binkov uses a sock puppet to lighten an otherwise somber subject.)
> Will this turn into a guerilla war, or will it go the way of total war? Or will it result in total capitulation?
Russia can take whatever it wants from Ukraine, at least initially. Russia's military is just too powerful, and there aren't any serious geographic barriers to prevent Russia from taking whatever it wants in the short term if Russia really wants to do so.
Whether or not it'll become a guerilla war is up to the Ukrainians. However, if the Ukrainians are willing to make it a guerilla war, and that seems likely at least on the western side, they can make Ukraine very hard to hold (at a horrific cost in Ukrainian lives). In the long run, if the Ukrainians are willing to seriously apply guerilla warfare, I think there's a good chance they'll make at least the western side too painful to hold if Russia goes that far.
I would not be surprised if Russia only took part of Ukraine, e.g., the easternmost parts of Ukraine, perhaps up to the Dnieper River, and perhaps also take Kyev. Russia gets lots more land, and it creates fear (which they may interpret as respect) in everyone around them.
> And another key question. What will Western governments actually do? What if the war gets really bad? Does the West actually have the balls to put real, biting sanctions on the regime? And will this crash the economy?
Western governments have already sent in a lot of military gear to help Ukraine. Western governments won't put troops in. They aren't obligated to do so (Ukraine is not a member of NATO), and the geography of Ukraine would make it hard to do anyway. Western governments have made that quite clear.
They'll put in sanctions. They will probably hurt Russia significantly. I think for Putin this is more about honor, and thus any sanctions will probably not be enough by themselves to force Russia out.
One huge problem is that the EU absolutely needs oil. Solar & wind get press, but they aren't enough today (or for years to come). The EU can't heat their homes or move their people without oil. Russia has oil.
Russia is more likely to grab eastern parts or the eastern side of Ukraine (east of the Dnieper). Russia could take the whole country, but is unlikely to keep it permanently due to guerilla resistance, so it either won't try or it will eventually give up western Ukraine. Sanctions by themselves won't be enough, but sanctions + guerilla warfare would plausibly recover at least the western side of Ukraine.
I do think that there will be serious negative consequences long-term for Russia, beyond sanction-related ones. It suddenly gives a powerful reason for other countries to join NATO (such as Finland and Sweden and a rump of Ukraine) and for them all to increase their military spending. It also gives them a very good reason to not trust Russia in the future.
This is a sad time.