I'm a newbie to knives and can't offer much in that vain but when it comes to hammock camping I feel I know a bit. I've been using a Hennessey Light Racer for the last 4 years on the Appalachian Trail doing section hikes of 50-70 miles. I've also got the Backpacker Asym and have oufitted my daughters with the same. So far I've hammocked comfortably at 17F and know I can go colder.
My Light Racer weighs 1 lb 6 oz and it is like sleeping on a cloud. After a 15-20 mile day on the AT it is truly a joy to evolve into it versus getting on the ground like an animal! No rocks or roots to deal with but you have to know that hammocks are colder than tents-much colder-bridges freeze before roads. But luckily there is a company named 'Jacks R Better' and they make underquilts for the Hennessey line of hammocks. The underquilts vary in weight depending on which you buy and that depends on what temps you expect. They suspend under the hammock so the down is not crushed by your weight rendering it useless as insulation. Inside the hammock I use top quilts, the ones I use are by Nunatak Gear.
The fly/tarp supplied by Hennessey is OK but I use one made by McCat, the deluxe, it give lots of dry real estate under the hammock.
I always suspend the fly independent of the hammock, that way it doesn't sag when I climb in....I also pack the fly separate of the hammock and suspend it first when its raining.
Hammocks also make awesome camp chairs and they make good sex swings too!
On the Appalachian Trail I'll stop by the shelters, cook, eat, socialize, sign the register but then I'll hike on another mile or two and then take a left or right off the trail and go about 1/4 mile then set up the hammock and dissapear into the woods.
Last year I had almost exaclty 100 nights in the backcountry and all but 5 nights in a hammock, the 5 nights not were in a tent because we were doing the Rae Lakes Loop in Kings Canyon and above 10,000 feet there were no trees.
In the long run hammocking wont save any weight over a lightweight tarp or tent but it is ultimately more comfortable.
If I know its going to be less than 20F I use a Speer hammock-not as comfortable to me as a Hennessey but Speer also has a product called a Pea Pod. The Pea Pod completely surrounds the hammock (thus use when bug netting is not needed) and is so incredibly warm.
When setting up a hammock make note of the surroundings, use it to block wind...if really cold and windy set up the hammock low to the ground-I usually set it up so I can sit in it without having to stoop, but when cold I set it up so the tarp will go all the way to the ground. Once I even scooped up leaves and make a 1 foot thick bed of them the length of my body and then suspended the hammock so when I was in it I was nestled into the bed of leaves to increase the amount of insulation.
www.whiteblaze.net has a hammocking section in there forums and then there is also hammockforums.com Either place has thousands of answers on hammocking.
I paddle camp as much as I hike and have even suspended the hammock above water in the mangroves in the Everglades.....