Once you have highlighted a word, you can drag the little blue dots around to highlight more or less text.
I'm not sure what sort of program you're looking for the reset the phone, I normally just power it off and then on again.
There is a built in email signature function in the email settings area. I'm not aware of a way to put a signature on a text.. maybe someone else can help there. btw: signatures on text messages are really annoying
