Definitely use an IR-to-Bluetooth solution for the PS3. It's the only way you'll get full control, including power.

For Kodi/XBMC, most proper MCE adapters should work fine, and I'm in fact using two different ones on different systems... although one of these days I'd like to try a FLIRC (don't know why I don't have one). If whatever you buy doesn't natively support USB/IR power on from full off, don't bother adding it. Sleep mode works just fine in Kodi, and you can configure it to basically work like a standalone hardware media player, with near instant-on.

I've been using a tiny HP Chromebox for a couple months now with OpenElec, and I have to say it's been the best (and least expensive) HTPC/media player I've ever had.