#1 my door thickness is 2"wii this lock fit my door ?
Yes I believe the bolt will expand to 2 1/8 inches for new doors
#2 How does the auto lock feature work? it just says in the description auto lock but provides no details.
You can program it to lock automatically after a number of seconds. If you put it on 30 seconds, then it will re-lock 30 seconds after the dead bolt is unlocked.
#3 is this water proof? i want to use on outside door that gets the rain.
Installed mine about a month ago, direct exposure (florida) and no issues as of yet. It comes with a gasket behind the keypad to prevent rain from entering.