If you have to skin the bacon yourself I find it is easier to remove after smoking. The smoked rind separates pretty easy with a fillet knife. The dried bacon pulls away from the rind easier and you can skin it like you are filleting a fish. I find that if I leave the rind on I am not losing so much of that great fat because of my lack of knife skills. I am not as good a knife guy as I should be and I get very frustrated trying to remove the rind from raw bacon.
If you have the option of selecting individual bellies knowing which one to pick is also personal preference. I have to buy them by the case or half case and I tend to just find the best, most reliable butcher I can and take what he can get. I can not find a butcher or grocery in the area that has whole pork belly in the display case. Some the oriental groceries will carry them but they normally trim the hell out of them instead of leaving them whole and their cost goes up dramatically. Your most important selection criteria is the green bacon's freshness. How is the color and smell. Does it feel or look the least bit slimy. There can be a big difference between a belly just out of the wholesalers freezer and the butchers display case. Another reason I buy case lots. The butcher orders it, she calls me saying it just came in, I pick it up right off the delivery truck.
As far as fat vs lean, who knows. I kind of like bacon fat so I may like bacon with a greater fat content. If you want lean bacon you can always trim off some to the fat and save for making sausage.
Good Luck, Bear has given you some great advice. I would defer to his recommendations. I am just trying to provide some personal experience.
The H Mart in Atlanta is an Asian market. Huge place. I do a little dance with the butcher there.
I leave the skin on for the same reasons...easier to get off after smoking and spending a few minutes in the freezer.