Gutting my Clipper

[DDandSavs]

My Clipper's name is DD. This is because those are the last two letters remaining on the front. It's a 1977, 24 foot, with a rear kitchen. I intend to live in it while homesteading in a space with a full kitchen and bathroom. So I really wanted to open up the space. The dinette, the shower, toilet, water tank, and some walls are all out, which feels good. I found some water damage under the water tank on the floor, so I can address that. We disconnected the water tank and put tape over the wires, but I'm worried this caused the whole drivers side electrical to go out. The outlet and the lights on the drivers side don't work, but they did before we took the water tank out. Any ideas?
While on the topic of electricity, the overhead lights automatically dim. Especially when there are more than one on at a time. I intend to replace them all with LEDs but after reading through some other posts, I'm realizing it might be because my cab's battery is probably dead? (DD is not starting right now but it did when I first bought it). Is that battery where the lights get power from?
While taking a wall frame out of DD, some of the ceiling noticeably sagged and I have an intense fear of living in a compromised space, but my fear of renovation parallels it so I can't decide if I should tear out the old ceiling or patch over it. Anyone want to tell me it's really no big deal to replace it? Or reassure me that patching it won't cause any new issues (like screwing through a wire) and as long as all leaks are sealed, it won't be a problem? This dilemma kind of exists throughout DD. There is water damage in a number of different areas. From the ceiling next to the A.C. to the wall behind the passenger side, a couple window leaks on the drivers side, and the floor under the water tank and below the oven in the back. In all these cases I'm torn between replacing or patching. What do y'all think?
On the note of the A.C., the condensation pools on the roof. Is this normal? I haven't been able to level DD yet since I can't get it started again, but maybe once it's level it won't be an issue?

Thanks in advance for any response. I'm very excited to have DD and to know there is an online presence of Clipper owners ready to share their experience and advice. Thanks for this space.
Savs