As usual, this has not been a textbook high tech air campaign by Russia! Makes you wonder about all those Russian claims about brand-new wonder-weapons!Well it can be that SAMs are still operational in Ukraine. Transports will definitely be a major target. This begs the question of why are these sites still kicking and not destroyed by SEAD sorties. Or why Russian ECM planes are not doing their job.
The Ukrainian AF is still in the fight (or was still in the fight a few hours ago). Whether they pose any threat to VVS in the air is questionable. As you said, Su-35s easily outclass the Ukrainian Mig-29s.
As for the last point, there is a reason why the PLAAF has adopted to NATO training styles.
Check Mate! Maybe, not!