Not sure I understand completely but try to relax at the sholder. If your guitar is slung too low it may cause problems like this. Also, try moving your elbow to a differen't position.

Practice difficult stretches further up the neck then move down to the frets by the nut. Your fingers eventually get acquainted to what they are supposed to be doing.

Your wrist does not have to stay straight. Like JTC said, a low slung guitar may look cool but it is detrimental to your technique. Notice many uber-shredders may have their guitar slung low when they're just slamming out chords, but when they have to do something more advance, they often put a leg on the monitor to lift the guitar up, or they tilt the neck way up to lift the neck. But I wouldn't worry about the wrist too much, unless you're experiencing pain.

well like 2 months ago i had a cast on it so it does hurt but thats most likely cause i broke it somewhat recently

i agree with dcunning, tighten the straps. health before looks

if at all possible, try to position you hand far away from the neck,like you are stretching to reach the fret board. also try to avoid gripping the bottom part of the neckwith your palm. allow some room there. this will allow the bottom strings to ring out clearly when you play...say...an E major chord. the idea is to allow the open strings to ring. as for the power chord stretch(1 and 3) you could also try using your index and pinky(more span to work with)...a little more comfortable on the hand.

Definitely raise your guitar...do not risk your writs for coolness :) especially if you hurt it recently.

Another thing, don't bother yourself much with wrist position for now, it all depends of your guitar's neck, your posture, your thumb's ability to bend(I can bend my thumb almost in a 90 degrees angle it the opposite direction, and it's kinda impossible to play in a good posture on some guitars).

The position of your hand and wrist is important, but for now - take it easy and relax :) :)

B.T.W. I do my power-chords with my index and ring finger, sometimes with pinkie.