Oh, one thing. While I STRONGLY recommend you find out exactly what the current is, if you want to take a wild (lazy) guess, just disconnect the alarm siren, it has become a leading cause of dead batteries.

Remove the cover under the wipers. All those screws must come out, removing the wipers is probably a good idea, but you might be able to bend the cover up enough and get in there - the siren is near the middle of the car and has a three-wire cable going to it.