. . . to remove, that is?

Car is a 1997 C230 w/ the white battery in the (frickin' &^&%*&) trunk. I've looked, and as mentioned in a post about a month ago, it has six cell caps w/ big Phillips-screwdriver crosses on them.

1) What size screwdriver do I need to remove these? I'd like to go to Ace or PepBoys and tell them what size, instead of calling somebody out, peeling back all the stuff in the trunk, and showing him the battery.

2) Another post has me wondering. Can I top up the cells with the battery in the car, or does it *have* to come out?

3) Distilled water, or tap water?

TIA,

__________________
* *
-- Paul W. (The Benzadmiral)
('03 Buick Park Avenue, charcoal/cream)
Formerly:
'97 C230, smoke silver/parchment; '86 420SEL, anthracite/light grey; '84 280CE (W123), dark blue/palomino