If the 18g wire you plan to work with is round, be prepared for some denting of the wire with your pliers, as with a round surface there is no way to firmly hold large, round wire with a flat surface (like the inside of pliers) and not dent it. If the wire is square and half-hard, you should have very few problems with dents as long as your frame is made 'on the square'.
Regarding adding cabs to the design, personally I would set my stone separately and then attach it to the frame (similar to the bracelet design on my book cover) or set the cab first, making the frame in 2 pieces, side-to-side, and where it joins on each side (like where you would normally put a bail) make sure the wires are long enough to be incorporated into the entire bracelet bundle. If done in this manner, the bracelet frame will usually have to be shaped to be able to incorporate the stone, by bending the wires out and around while planning the main bundle, so the stone has room to be placed between them before taping and then wrapping the entire bracelet.
Of course, I suggest that you make the actual pattern you are looking at first, so you are familiar with how the designer/author suggests making their design, before you plan to alter it.
Answer contributed by Dale "Cougar" Armstrong