If you go with a JRB BMBH then
- definitely go with a tarp on the larger side, e.g. the JRB 11'x10' or the Speer Winter Tarp
- since you're just interested in "basic" for now, and almost surely you have already a sleeping pad, then you can most likely slip that pad into the pocket provided for it on the BMBH. Underuilts are great, and when you become fully indoctrinated you see the wisdom of reduced length quilts, but for getting started you can forgo that cost, no problem.
- Any sleeping bag that zips most of the length of the bag can be used in a hammock, but the preferred method is to unzip it, and open it up as an overquilt.
Chances are that after picking up a BMBH and a tarp you'll have almost all of what you need.
That said, I'm told JRB is running a sale on their quilts right now...
I will also re-iterate what Narwhalin said. We don't do bananas here. Properly laying on your back in most camping hammocks you are largely flat, with a slight rise up your spine. It's kind of like be stretched out in a lounge chair that folds way back.