Yeah, I wouldn't worry about the feet.

No substitute for experimenting in your room. I don't know that anyone can give you absolutes about any of this. The distance from the ports to the back wall isn't really critical as long as they can breathe (so, like 2" minimum). The bass reinforcement is going to come from modifying the distance between the bass drivers and the adjacent surfaces. So, yes, moving them in and out from the wall will matter, but not because of the ports.

bibere usque ad hilaritatem