#2
As for theory, the most useful things in guitar music are chords and scales. Just go to your local music shop and look around. I have this book (which i'm not sure where it is anymore) that is called scales and modes for guitar or something like that. Learning scales will allow you to create different sounds while writing or soloing. Also, its sometimes interesting if you have a chord book to look through and find some really cool sounding obscure chord. Also it will help to teach you fingering patterns. Also from what i hear, Scar Tissue is a good read if you just want some entertainment.
#3
To get the true depth of theory meethinks, books can only go so far unless you have patience of steel. A tutor is the best way to go, as long as they're a good one.
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You're just another brick in the wall