I can only speak to a few of those--I've got an H/K 525, so my knowledge about current recievers is quickly declining.
On my 525, I've never had the fan go on.
A-BUS seems to be mostly useless unless you're going for a
custom install with in wall speakers in your house. Also, nobody knows anything about it, and quesitons about it on these forums will be greeted with silence and chirping crickets.
The multizone on the 525 is confusing, poorly documented, and hard to implement.
The remote on the 525 stinks. The 635 may be improved.
On the DenonLink thing, you'll need a rather expensive Denon transport to use it (ie, expect to pay about as much for that as for the receiver).
The bass management on the H/K is really nice. Far less confusing than the Denon, at least as far as I can tell from the amount of questions. Also, since you're going to have a VP150, M60s, and QS8s, you may wish to take advantage of it; cross the VP150 at 80 Hz, the QS8s at 100 Hz, and M60s at 60 Hz. (these are just examples off the top of my head, people...) With my setup (M50s, QS4s, center channel playing through TV speakers), the need for this is exaggerated, but it's really nice to have. Plus, I don't have that LFE or LFE+Mains setting at all.