#1
I have a friend who I want to start a band with but can't quite get to play stuff with him. I was in band a couple years so I know basic music theory (timing, keys) but he pretty much learned guitar by playing riffs and such. He thinks in more of a guitar tab mentality when it comes to playing while I see things like eighth notes and scales when I play. I pretty much just want to get him to have that tight, "quantized" playing so he can feel the music rather than play notes when it sounds about right. Are there any ways I can get him to teach himself to be able to get these aspects down? We have awesome chemistry as bandmates and it would be perfect if we were able to play together better.
#2
You've just gotta sit down with him and help him learn the parts in time pretty much. Maybe bring a metronome if you've got one. If he wants to improve, don't be afraid to "baby" him through riffs/licks and if something is too hard for him, just help him learn it slowly. In the end, it'll be him who has to put the time into practicing the parts, but if you sit there with him and watch him (correcting him if something he plays is wrong) he'll get it.

Also, helping him work things out by ear is probably really helpful too. The less you have to rely on a tab, the better.
#3
Motivating someone is a hard thing to do. Maybe try showing him how its helped you as a musician. Other than that, you can really only hope he decides to work at it for his and the band's benefit, and help him with it if he decides to. Show him the ways you learned key, time, etc.