I know something like this is possible in "normal" ICS roms (as a hack), so i guess with some tweaking you could do it to MIUI too. Unfortunately i'm afraid it's not going to be easy: http://forum.xda-developers.com/showthread.php?t=1364757
(i tried googling it, but it only showed me flashable zips for older versions of miui, so you're going to have to do it yourself)
Yeah, but I made the soft buttons smaller so you can still use all the buttons even though a little part of them are cut off. And this is only in the camera app