I have tried using hammocks several times and never enjoyed the experience. Furthermore, I am near or above tree line which makes hammocks useless.  I would suggest you check out people who love hammocks such as Sgt Rock’s Hammocks 101.

In warm weather nothing will keep you as cool as a nice hammock. In moderate weather many people find quilt over them. and a aluminized windshield shades under them work well.  In cooler weather you will need more insulation.  My limited experience is that insulation which is adequate for when I was on the ground down to around 30F kept me almost warm enough at 48F in a hammock. The Gossamer Gear Thinlight Pad (1/4 or 3/8″) looks like a good under insulation layer for cool-moderate weather. I won’t recommend the 1/8″ Thinlight because it’s too easy to hole and isn’t stiff enough to stay in place. In colder weather I would encourage considering using an under quilt. There are a variety of companies that make under-quilts.