I agree with Mr Verber about the backpack. I have used both the Jam2 and the Conduit (currently use the Conduit mainly and prefer it to the Jam2), but if you're new to backpacking in general, I think it's a much better call to go with a fully framed pack that's designed to take all of the weight off your shoulders. Also, tarptents are great, but keep in mind it's still a tarp and tarps tend to be an acquired taste. Definitely make sure you love tarps before shelling out $200 on a tarptent. The best time to try out tarping is right now, while it's still too cool for too many bugs to be crawling around. I don't worry about snakes when I'm tarping because they tend to be nocturnal hunters. They bask in the heat during the day and would probably be suspicious of a warm place at night.
If you would like to hike at night on a trail that's anything less than a clear "highway" cleared of leaves and distinct from the deer trails; then it's worth the weight to just bring an 8 ounce super bright headlamp like the Petzl Myo. Otherwise, if you see yourself stopping at nightfall (certainly nothing wrong with that, especially in the summer), then a lightweight LED would definitely be my choice.
My favorite pants are a pair of Cloudveil polyester/nylon stretchy pants that are not made anymore. I don't remember the model name, but the important thing is that they dry quickly, are a little stretchy (not like sweatpants, but not like blue jeans either), and have zippered pockets. Light weight is also a good indicator of how breathable or warm the pants are. Mine weigh about 10 ounces. One pair of pants that still is being made (I think) which would be comparable is the Arc'teryx Gamma LT pants. They are made of Schoeller Dynamic, which is quick drying, lightweight, and stretchy. I am not a fan of convertible pants, but then again I've never thru hiked. I usually just wear pants the entire trip if the evenings will be below 45 or so and I wear running shorts and bring thin fleece tights if the evenings will be above 45 or so.
I personally would go with a sleeping bag (in fact I personally do). The Western Mountaineering bags are the best out there and compare very favorably with quilts in terms of weight to warmth. For instance the Summerlite is a 32 degree mummy bag that weighs 20 ounces. It has a full zipper to unzip into a 32 degree quilt with a small footbox (and WM hoods are the least bulky I've ever seen so it's essentially a quilt). At first glance, this does not compare favorably with the Golite Ultra quilt, which weighs the same but is rated 12 degrees lower. However, you'll need a pretty beefy insulated hood (perhaps an additional 2-4 ounces) to get the Ultra down to 20 degrees (and that's given the probably erroneous assumption that it's accurately rated to 20*F), and if you want it to be truly draft-proof, you need a bivy sack as well (6-7 ounces more weight). Now compare that total weight with Western Mountaineering's 20 degree bag, the Ultralite Super, which weighs 27 ounces, is accurately rated to 20 degrees, includes a hood and zips up for complete draft protection. Now that Golite Ultra starts to look a lot less ultra light.
Also, Jaiden's got some good advice. The Gear Swap here on BPL gets such a high amount of activity for a reason! We all have to re-buy gear, even after doing lots of research, even after we think we've found the best piece of gear there possibly is or could ever be. Don't be afraid to buy used.