Vr, try getting a little advice from someone who knows batteries. Each type of battery has it's special needs and applications. I found helpful, knowledgeable
and friendly advice from a guy at Batteries Plus. You don't have to buy their stuff unless you really want to, but I bet they'll advise you on the best way to encase your batteries, charge them, etc.

Raymond, a good friend of mine told me to make sure my battery case was vented. He said it was because of the potential buildup of gas, even from SLA's. The important thing is to be sure there is a way for any pressure to escape without letting water in.

I've tried my hand at soldering and I still have to learn a few things, but I'll practice on old wires until I get the hang of it. The Liquid Tape works very well for waterproofing connections. Once it's dry, it's a bit like rubber. When it's wet, it's a bit messy and wants to drip, but it dries fairly quickly if it's not applied too thickly. It works best to apply it in layers.

Most 12V accessories that I've used don't seem to care about polarity, that is,
which wire you hook up to the positive and which to negative battery terminal.
But you have to be careful, because some accessories will only work when hooked up exactly right. My xenon strobe is picky like that, but fortunately it is protected from damage if the polarity is wrong. Just be sure to read all the instructions that come with any accessory to prevent damage to any of your equipment.

Also, fuses are essential. They prevent accidental system overloads which could be a fire hazard, even with 12V systems. I use a 10A fuse. Any current higher than 10 amps will burn out the fuse before any problems happen.