Why don't you just wait till everyone is up, then amke a game of it.?.
if this is a normal home alarm, the battery is backup, there fore the alarm runs of house power. disconnect the battery and change it. the AC power keeps it on.
Switch the alarm off, then change the battery.
It depends. Did you need to grapple to get over the wall, and do they have CCTV?<br />
Depending on their security systems, you may have to figure it out yourself, get in there and get out again before anyone has the chance to answer.<br />