The Gizmo is a good choice. Unless you're planning on doing serious night-hiking, really any headlamp works fine. The biggest task you're likely to use it for are midnight privy excursions. Personally I like the Petzl Zipka's, since they don't have a strap that takes up space in the pack. Seems like half the time I'm using the light I'm just holding it in my hand anyway.

The poles are good too. Try them out in a store beforehand if you can, just to make sure the grip and strap are comfortable for you. The rubber grips aren't always the greatest in warm weather because they get sweaty, so you may want to think about stepping up the cork grips for a little more money.

Your Exped link doesn't work, but I'd guess you're looking at the Airmat? You're probably going to want more insulation than that during the cold weather portions. The Big Agnes insulated Aircore mats are a pretty good compromise for weight/insulation/price.

The Kelty is a really good value in that price range. In a tent, with a good pad under her, she'll likely be fine with a 20 degree bag. Having a good set of baselayers to sleep in when it's really cold is a good idea too.

9 liters of food storage for 2 people is probably too small. I used a 10liter bag solo and there were times when cramming a full resupply in there was tricky. But I'd probably recommend a 10liter bag per person over a single big bag, just for the ease in packing and hanging. For food bags I really like using bags that have a webbing handle on the bottom - it keeps all the weight from being hung by the plastic buckle, and points the opening downward away from the rain. If you hang it opening down having the bag be waterproof really isn't all that important. The nylon will shed almost all of the water, and all of your food will likely be in plastic bags inside there anyway.

You can skip the groundcloth. More trouble than they're worth really. Just spend a minute or two inspecting the site for pointy twigs and rocks. I've got a BA tent with hundreds of groundcloth-free nights on it and it's floor is still in perfect shape. (If you would poke a hole, it's easily repaired anyway)

Yeah, poncho's suck. They're great if you're standing still in rain that has no wind with it. Driducks are fine, you see lots of them on the trail. A little care when passing by branches aong the trail and they last. Duct tape patches them up pretty well if you do tear a hole.

Trash Compactor Bags make excellent pack liners: the 15-18 gallon size works out to be about 65liters, so it's a perfect size for most packs, and they're a thicker/tougher plastic than a regular garbage bag. (to get a regular garbage bag in as thick as plastic you otherwise have to buy the huge 55 gallon heavy duty bags). It'll last a month or more with if you're nice to it, and they're readily available at grocery stores along the way. Actually you see a lot of partial boxes of TC bags in the hiker boxes at Hostels - people will buy a box of 12 bags even though they only need 1 or 2, and then just leave the rest behind the next hiker that needs them.

When you get closer to be ready you should post your whole gear lists for both of you in here...people usually get pretty good feedback.