cab switch is no big deal. unbolt everything, call a few friends and lift.
theres a few versions of the sound proofing junk, some goes with a heat gun, some goes best with dry ice and a mallet. its no fun no matter how you cut it. im not quite clear on metal lip question. a return flange can be put almost anywhere but you can't form into it because the surface area is maxed to the form it already is. if youre attaching anything with much weight youre going to want a backing plate more than a lip anyway because it will tear like cloth as an attachment point.
good luck
