I know a professional chainsaw carver and we had this discussion a while ago about how he finishes bar tops and benches, its something like this product (or maybe this exact stuff for all I know):
He said its a little tricky to work with, but looks great if you are going for that sheet of glass look. So, if you go this route make sure to do some homework on how to apply it before jumping into the project.
For your second question, I'd do the lighting last, once everything is built then figure out what a comfortable drop on the lighting is when you are sitting at the bar crossed with what looks visually appealing when standing in the room. There is no measurement that can tell you what is right for that sort of thing.