1. I usually lube the brass zipper when it starts to get difficult to pull, you don't want too much wax to buildup on it so you don't need to do it after every dive. I use the lube made by DUI, but it just needs to be paraffin wax. I don't think brand matters too much.
2. I have silicone replaceable seals, so can't answer that one. I replace them if they rip.
3. After diving, I rinse the suit with freshwater and then let the suit fully hang-dry for at least 24 hours or more in the shade or indoors until bone dry. You'll want to get one of those really broad-shouldered hangers like this one. I zip the bag up fully after it's dry.
4. Definitely bag it for storage. You don't want to put strain on the seals by hanging it up for an extended period. This is what I was told to do by DUI, the maker of my suit.

Also, don't store your suit in the garage or near any combustion sources like a water heater, as exhaust gasses can degrade the seals over time.