Misc Parts:

Fins:

Here you have some choices to make. There are three mounting systems to look at, 1) glass on, 2) fin and fin box and 3) FCS system. The glass on fins are the cheapest and lightest way to go, but are prone to breaking and are more work and harder to install right. The fin and fin box are what I went with, you glass a fin box into the board after you glass it and the fin slides into this and secures with a screw, also with this way you can remove the fin so that it doesn't get broken when you are tranporting or storing the board. The FCS system is the third choice, I really can't tell you how exactly they work, but they are more like glass on fins, but are removable for travel and storage, and are more expensive.

Leashes and plugs:

There are a bunch of surfshops on the internet where you can get a leash, look around and find one you like. The plug is what you attach the leash to on the board, these are available from Fiberglass Supply.