PS3 controllers and most RF or BT PC peripherals should be fine. I've never had any issues with PS3 controllers or Logitech "Unified" RF devices, they're good for 30-60 feet. The older RF stuff was only good for 3-6 feet, but both Microsoft and Logitech peripherals with the mini receivers are 30+ feet range. You might have to do some sort of IR repeater to control the receiver, cable box and the like. Look in to Logitech Harmony stuff.
Sounds like a nice setup, fairly similar to mine. I've got an old PT-AE2000 with a dying panel and a 106 inch screen. It's pretty awesome paired with a fast HTPC and/or PS3. I use a Logitech Performance MX mouse and a K800 keyboard. Both seem to work fairly flawlessly, although sometimes I can get some mouse lag or repeated keystrokes, but that only seems to happen when the CPU is pinned. It's something I've noticed on and off with numerous KB/M setups over the years, something about having the CPU maxed out can occasionally cause some interference issues with RF devices, but it's generally never been a serious issue. I tend not to play any "twitch" style FPS games on the HTPC anyways.