I hope your aware the projector must be mounted inverted at or slightly above the top of the screen. It may be possible to mount it as you suggest using picture detail robing digital keystone. A non tab tensioned manual pull down screen is most likely to have waves in it out of the box your will develop them soon after. Without knowing the ambient/reflective light control in your room it's hard to say what type will work. As far as moving your amp the best solution is a universal remote with remote hub capabilities that will also eliminate all the remote clutter.
"Smart enough to know better, to old to care" ------ Dedicated Bat Cave Home Theater, JVC RS49U/Mitsubishi HC7900DW Projector, 110" 16:9 Jamestown screen with variable power masking for CIW 2.50:1 to 16:9, Marantz 7009 with 7.1.4 Atmos with Ohm mains,3 DIY Subs (2 15" (1 ported, 1 sealed and a 12" 4th order bandpass), 1 DIY butt kicker, Custom Built HTPC, 18TB DroboFS NAS