it could be a bad ear speaker or a bad light proximity sensor.. if the sensor goes out then the ear speaker won't work.. a way to test the sensor is to make a call and cover the top of the phone.. if the screen goes black then the sensor is good and the ear speaker needs to be replaced. if it doesn't go black then the sensor is bad..

sounds like they sold you a bunk part. for the rotate make sure your portrait orientation isn't locked... when you double click the home button and then go all the way left where you see the ipod, back, play, forward, and then the icon all the way left it what you are looking for.. make sure that is not locked

if it's only the metal part that fell off, if you're awesome you can glue it back... the other way would be replacing the whole back housing because the volume button is stuck between the bezel and back plastic

sounds like a bad flex cable, make sure there isn't any debris where it connects. and make sure the metal where the volume controls adhere to is clean of any old adhesive or debris

you could have removed the old mesh from the original display or bought a new one for the repair. for the photo problem, make sure there isnt any protective plastic covering the lens area. if there is you were suppose to peal it off before installation.

yeah make sure it's the right lcd.. both the 3g and the 3gs look exactly alike except for the connections. the 3gs will not fit on the 3g board. if it's the right one. try another lcd.. if that doesn't work.. a pin could be burnt on your boards lcd connection. that would need to be resoldered on. if the pins on the connector look fine and if your phone is a 3gs, the backlight coil could be out. and that also needs to be resoldered on the board

if replacing the lcd doesn't work. it could be there is a burnt pin on the lcd connector on the board or the backlight coil is bad. either one requires soldering on the motherboard and is pretty difficult. but usually either one of these is due to liquid damage. try applepierepair.com. they are masters at this stuff