Welcome, 72mustang!
Unless your room is gigantic and/or you plan on listening at earsplitting levels a receiver should be good enough. If not, make sure the receiver has preouts so you can hook up a separate amp.
Many people here have the VP150 on top of the TV and I can't remember anyone complaining about magnetic interference.
I wouldn't worry too much about the rears. Just use the speakers you've got right now. Later on, if you want, you can change to the QS series. I've been meaning to get some for years, but have never ponied up the money for them. Of course, once I hear them I may say they are a must-buy!
As for subs, you may find the M80s adequate by themselves for music, at least. If movies are your thing, a sub is a must. Generally, a ported sub will play lower and may offer a little more oomph. Sealed subs generally don't play as low, but may sound a little "crisper." I say generally because it's very subjective and there are variences between subs.
Well, I've never heard the M80s and I don't know how they sound at low volume.
