For controllers, I used TouchOsc originally (http://www.youtube.com/watch?v=g_PWYj1j_do
), but now I use Lemur with my own templates and it is truly awesome. As far as hardware goes, I've had a lot of them (irig, Irig midi, ampkit, Griffin guitar connect, Tascam im2, Griffin imic)and I recently bought a Tacam IU2 and love it; 2 mic pres with phantom power, guitar in, spdif out, midi I/O, great monitoring, and you can charge the Ipad from it! Also, it doesn't require the camera connection kit so it works perfectly on my Iphone as well. It's built a little flimsily but it sounds great. Stay away from stuff that uses the 1/8" input.
Comp1: Windows 7 64bit, Gigabyte GA-X58A-UD3R, Intel I7 970, 12 gig Patriot DDR3 ram, RME Digiface, Geoforce 66000 PCIe, , Cubase 7.5.10
Comp 2:Windows 7 64bit, Asus P5W DH Deluxe, Q6600, 8 gig Corsair XMS ram, , MR816 X(x2) VE Pro