You wrote a lot... so I will only respond to these two comments.
First off, you might want to check military spending by Country for the last half decade or so...
It's a safe link. As someone interested in military history, you might find it interesting. It breaks down military spending by absolute USD value, percent of GDP, percent og Gov't spending and other metrics. Russia actually falls behind quite a lot of other countries, especially the US but also France, China, Japan and other countries that haven't invaded anyone recently, or even ever.
The second point you made I think is completely untrue, and no I am not dimisnishign the events of the last few weeks and especially today which is extremely serious.
However, Russia doesn't want and can't afford to occupy all of Ukraine. It would be a bloodbath on a scale they haven't seen since WW2 and make their invasion of Afghanistan seem like a training mission. Ukraine is no threat to Russia and most Russians do not want to occupy a neighboring country, and it's hard to see how Russia could even do it logistically without sustaining huge casualties daily, which would not play well at home.
Russia (or more accurately Putin) wants to provoke a response from the West to justify his grip on power and the need for border-states that are exclusively friendly or completely passive towards Russia. His paranoia about the expansion of NATO is real and not just a pretext, even if it's unfounded. We don't know for sure, but the strategy immediately is likely to just diminish Ukraine to a basket-case of civil war and factionalism so it can never be a cooperative part of the "West" (i.e., either NATO or the EU).
Ukrainian nationalism would make it almost impossible for the entire nation to be subsumed into Russia, and attempting to do so would destroy Russia's economy and likely see the end of Putin.