sound like there is circuit damage some where on the motherboard, if it still under warranty put back together and take it to apple store just make your water sensor stickers is back in the right place as apple will open the back to check for water damage. other wise you will need a powerful mircoscope and soldering skills.
well i work out what was wrong the facetime and youtube issue, just had to leave for 24 hrs and everything worked again. so i do think! once the motherboard is disconected from the battery it takes about 24 hours to reset itself. as for the camera issue never had that problem? i assume you connected everything tight in it's place. maybe worth tryin a new front camera and see if that the problem!!!