can someone please explain to me...

[dutch777]

7. Specifically he wants the buffer states that isolate RU proper from the west AND have important industries

Ukraine was a major wheat and grain producer that filled Moscow's coffers and silos plus had many hard manufacturing industries RU wants. And if you are going to invade Russia, Ukraine is the southern route in. Northern route into Russia is thru Poland hence that dynamic for Putin. But the Poles have had enough, possibly the strongest and most capable land army in NATO right now which further worries and ticks off Putin. And some of it is just bragging rights as to who has the most influence in Europe and the more countries in the EU and NATO the more diminished Putin feels.