body areas i need to be careful about

Vastus Medialus weakness:
http://www.exrx.net/Kinesiology/Weaknesses.html#anchor13238820
sometimes when walking up stairs or motions that strain my legs, i'll get a sharp pain in my knees and the muscles will give out.

Suprasinatus weakness:
http://www.exrx.net/Kinesiology/Weaknesses.html#anchor3503966

Infraspinatus weakness:
http://www.exrx.net/Kinesiology/Weaknesses.html#anchor3549775
my shoulder hurts sometimes if i rotate it wrong and i have to make sure to warm it up good before i do bench press.

Shoulder Internal Rotation Inflexibility:
http://www.exrx.net/Kinesiology/Inflexibilities.html#anchor13299557

shoulder articulations:

http://www.exrx.net/Articulations/Shoulder.html#anchor109903

http://en.wikipedia.org/wiki/Rotator_cuff

rotator cuff muscles:
http://www.exrx.net/Muscles/Infraspinatus.html
http://www.exrx.net/Muscles/Subscapularis.html
http://www.exrx.net/Muscles/TeresMinor.html
http://www.exrx.net/Muscles/Supraspinatus.html

exercises covering all the rotator cuffs (+ teres major):

http://www.exrx.net/WeightExercises/Infraspinatus/DBLyingExternalRotation.html
Infraspinatus
Teres Minor
Supraspinatus (when shoulder is abducted, i.e. not resting on body--raised slightly in the air)

http://www.exrx.net/WeightExercises/Subscapularis/DBInternalRotation.html
Subscapularis
Teres Major


wrists
http://www.exrx.net/Lists/ExList/ForeArmWt.html#anchor1936059