A BC is key. You want a BC that is streamlined. To get a streamlined BC, avoid "features" such as padding in the back and cummerbunds. Go with a bladderless (AKA single bladder) design. These features are available with a vest style as well as wings. An excellent example of a vest BC that will give you years of excellent service is the Scubapro Classic Sport. The Classic is a poor choice, IMHO, while the Classic Sport is a very good choice.
I've used all different styles of BC's and the style doesn't make any difference in performance. If you do decide to go with a vest style, remember they are more comfortable and work better when you leave the chest strap undone. Also keep in mind most people use a BC that is really too big for them, proper fit is important.
As for a regulator, that depends on the type of diving you plan. If you'll be diving shallow and only with folks you can count on to monitor their air, I'd recommend a workhorse like the Sherwood Brut or Magnum. If you'll be making lots of deeper dives, especially with unknown dive buddies, go with a high performance regulator.