I have this old guitar that is chunky/uncomfortable and big. I was figuring i would take an electric sander to the body and sand it down to where it felt good. Then, I figured I would repaint it with maybe a sunburst finish, or if the paint was still in the wood I would pick another color that was solid and give it a couple coats and some gloss. Then I'd put the neck back on and solder everything back in and get it set up, etc to make it normal again. is this a good idea? will sanding everything down be pointless or what will happen? This is mostly just a fun thing to get into wood working and have a half decent product. I'm not looking to have a gibson in the end.
It really depends on how much you are taking off of the guitar if it is only like up to a half inch, sand will be fine but take a while even with a power sander, but even that is a stretch.
unless taking wood away from the top of the guitar.

If more than a half inch I would recomend a band saw, whih you probably don't have, so use a resipricating saw.
all i have is a jig saw when we're talking power saws. i really want to sand it no matter how long it takes just so i have complete control over the shape of it. like so i can take it off bit by bit. so you guys think it will work to sand it and everything? like it wont suck horribly?
well i cant remember a time when sanding hasnt sucked horrible lol
but i think youll do a fine job at whatever it is your going to do