hey there, well yes you sound like you are in the beginning stages of puberty congradulations. im not sure why your testicles are hurting. have they gotten bigger? sometimes they will ach on and off for no reason but any severe pain should make you go see your doctor. out of curiosity did you happen to masturbate before your testicles started to hurt? for instance did you masturbate then shortly afterwards they started aching? also it would be a good idea to check for any lumps on your testicles (its best to do this in a hot bath or shower when your scrotum (ball sack) is relaxed and loose. check for any lumps. keep in mind the thick lumpy area in the back of your testicle that connects to the chord is the epididymis and is suppose to be there.
dont worry about the leg hair as you go through puberty more your leg hair will grow more and becaome much more noticable. right now ist thin and short so the way the light hits your legs when someone else looks at it makes the hair hard to see due to the angle.
i hope this helps and if you have any other questions just ask