"haven't found a way to get to a certain part of a sentence/word using SMS or keyboard (like the L/R arrows on a computer keyboard)"
press and hold, and you should be able to move the cursor to where you want.
Thanks, discovered that right after I wrote that!
...my Home button seems to be working fine now...
Panasonic TH-42PE7U plasma, Toshiba HD-D3, PS3, Shaw DCX3400, Yamaha HTR-6160, Polk 6.1, Belkin PF30, Harmony 700