Quite a bit of info on both of those here and in the whiteblaze archives - just do a search.
My system changes pretty often, but here's an example.
For 50s when bugs might be a problem, I use the JRB 3 season set w/ the Hennessy. I've been playing with the Warbonnet but I've only tested it outdoors with the quilts once...worked fine.
For 40s, I assume bugs won't be a problem and take the DownHammock and JRB NS. A half-length CCF pad insulates the legs b/c the DownHammock is only insulated down to my thighs to save weight.
For 30s, I use the DownHammock and JRB NS and take extra insulating clothes.
Last time I was in the 20s/teens, I used the Exped Downmat 7 with the Sierra Designs Wicked Fast bag and the JRB NS on top of that. Probably would have used the DownHammock but my son was in it.
Last time I was below teens, I used the Downmat, JRB NS and PeaPod...I was VERY warm and had to vent down to my waist a few times. I didn't really like fidgeting with blowing up the pad in conditions like that, though.