Can I make it so that the screen doesn't turn off when I'm on a call?
Yep, and this one is easy.
Go to your Dialer, hit Menu and go to Settings. Simply UNcheck "Auto screen off during calls". This turns off the proximity sensor, and now your phone will keep the screen on during calls.
That was super easy! Also, the root guide you posted makes it look pretty simple, I think I may try it.