If you have a table partner, and you plan on sharing a table, go ahead and apply for a full table together. Half tables are limited, and are generally for people who are applying on their own, and don't have the need for a full table. You may request that your half table be put near a friend's, but I can't guarantee that that will happen at this point in time.
I believe that the contract has been changed this year, so that only one extra badge, other than what comes standard with your table, may be purchased. I'm not sure why this is the case, but I'll look into it and get back to you on that.