There are no stupid questions. We are here to help. So I'll try to explain some for you.
1. The bumpers will support a high lift jack. There are some rockers on the market that will allow the side of the jeep to be used as a jacking point also just make sure they are strong enough.
On another note, the high lift is very dangerous to use if all safety precautions are not used. It should only be used as a last resort. A lot of members here have never used one and don't even carry on in there rig.
2. All of the drain plugs are underneath the carpet. Just lift the carpet up, they will be little black rubber plugs. There should be one in each footwell and a few in the back.
3. A jeep is not completely water proof. I have been stuck in a torrential downpour and after my air bag light stayed on for a week, but luckily went out again. The electronics can be affected, and the seats and carpet can mold and smell if not dried out. You can look at buying an emergency top at quadratec.com or any other vendors site. I believe they are about 70$ and are meant to protect from most water when a major storm comes through.
Hope this helps. Happy Jeeping.