I use a swivel but know guys who tie direct braid to mono. If you go with swivels get some croc swivels from cape cod tackle. They are small and the best you can get for pretty short money.
Cape Cod Tackle: KROK SWIVELS 50 pks
size 7 is plenty big.
Get some breakaway clips while your at it.
Cape Cod Tackle: Breakaway Snaps
For leader material you can grab a 50 pound spool of clear Ande from your Local #^^^^&'s or Sports Authority.