I'm going to go bass fishing, and I'm going to use live bait in a lake lewisville's marina in Fort Worth. However I'm not sure what to really use as a rig. Do I use circle hooks or a live bait hook. Should I use a bobber if so how big does it need to be for the fish not to pull it down. Any tips would be much appreciated 

First, make sure you can fish in the marina. A lot of them around here don't allow bank fishing and get pretty testy about folks fishing them in general.

 

For a live bluegill, I prefer something around a 4" gill rigged on a 1/0 Kahle hook under a cigar shaped Thill slip float. Another option is freelining, which is effective but is a problem around obstacles because the bluegill will wrap you up just like a bass will. A small, sturdy live bait hook like the ones Gamakatsu makes work well to nose hook the bait and let them swim around to try to find a big bass for you. 

Here is what I would use don't know how many bass have fallen for them while fishing for pike and musky you can order one or make one out of heavier line...https://www.muskyshop.com/sucker-rigs/