I think you'll be fine with a Winter Wren, since, unless you are really a cold sleeper. I can sleep in a standard Wren to 25, they work great in a hammock, especially a Hennessy.
Keep one Nalgene for a bag warmer. Get two 32oz Gatorade bottles. I love playtypuses, but I would carry one in FEB.
I'm dubiious about the Neoair, I strongly urge you to spring for the Jacks R'Better 3-season set (Nest underquilt and No-sniveler top quilt) Use the Wren until it warms and then use the top quilt. You'll likely need an evazote pad or a ridgerest in addition to the Nest underneath you until April or later. I'd carry a full ridgerest. I strongly urge you to get this hammock thing worked out NOW, no guesses, you'll most likely get it wrong. Check out
www.hammockforums.net
Your pack is likely too small. A ULA Catalyst is light and large enough, You are going on a winter hike.
You didn't say anything about a tarp, the stock Hennessy tarp is woefully inadequate. I'd reccomend a Macat Deluxe from OES. You might also consider a Winter Tarp like the one from Speer Hammocks. OES has a winter tarp in the works. Spinnaker fabric will lighten your load a bit, and you'll wallet a little.
No Ursack required, you ain't above timberline. Get the bear bag line from Anti Gravity Gear and a roll top dry bag for a food bag. Learn the PCT method of hanging and don't be a moron and think you'll figure it out on the trail, you won't. Read the online article at BPLight and practice until you have it down.
I use a homemade gravity filter (7oz) following these directions:
http://www.tothewoods.net/HomemadeGe...ityFilter.html
I use katadyn foil packed tabs for backup, they don't get soaked or freeze.