I haven't sold there only bought, but I will try to answer some of your questions if possible.
How do I know when I am paid? Your "Credits" will increase, plus there will be some kind of transaction history in "Your Auctions" section of your profile
Also like ebay do they have shipping labels you can print? I don't think so, but shouldn't printing labels through Paypal work?
Or how do they go about getting you the buyers address? Buyers are required to provide sellers with their mailing address upon winning the item. If they don't provide the info the seller can't send and no credits are transferred. Another way to get the buyers address is if you charge a shipping fee (so they will have to use Paypal which gives you the address usually or send payment for shipping), it is an option but some buyers don't like to bid on auctions that charge for shipping since the main concept of Listia is to have "free" transactions with no actual money changing hands, just the credits.