questions on busing

I think what you are saying is all good and I do things in a very similar manner.  Buses give you lots of control at the end of the day.  In fact when I mix I am mostly fine tuning buses and not tracks so much.
 
I don't process the main stereo buss at all I am one of those who does not believe in it.  I may check things into a compressor but I don't print with it on though.  I prefer to master a week later and do all that later on.  I believe it results in a better sound.  But others don't agree I realise that.
 
One trick is to put the vocal compressor on the vocal buss and NOT on the track at all. There are a couple of reasons for this.
 
If you manually ride the vocal level at track level then you are controlling the signal flowing into the vocal compressor which is later on at buss level.  Also if you automate vocals at track level say pull a loud section down then you are making much less work of the main vocal compressor hence it will just sound better. Vocals always sound better when the main compressor doing the vocal compression is not working that hard. ie ratio 2:1 max and not lots of GR. (smaller ratios mean a bigger sound which means you can pull vocal levels down, maximum illusion, minimum voltage)
 
The problem with having the vocal compressor on the track is that it is always working the same way regardless of track fader levels so loud bits will hit the track vocal compressor much harder.
 
It is also nice to send the vocal level into its reverb from the track NOT the buss. That way you are sending a non compressed vocal signal into the vocal reverb. Loud vocal bits mean more reverb and softer vocals means less reverb. This is a nice effect.

Yep, I have been known to do that too.  I tend to use busses as needed.
 
In other words, I don't set up a bus in many cases just to set up a bus. Some are pretty much SOP now days. I almost always have a lead vocal bus, a BGV bus, a guitar bus, and the rest are on an as needed basis.  I will sometimes split the guitar busses into electric and acoustic due to different EQ requirements.
 
I have set up an instrument bus for a project after the fact because I needed to lower the instruments as a group and the mix with envelopes was done. Pop in a bus, route the band to it, and waa laa, instant instrument volume control.
 
I use a main vox bus because I can put the FX there and if I need to fix the vox ME can go into the track and be processed without printing the reverb and compressor.
 
2 or 3 busses besides the master are the norm these days but I've seen some projects with more than that. Like I said, it all depends on the needs in the project to get the desired results.