I did use a dri-ducks jacket in early season for a while on the AT; despite blowdowns I didn't shred it, but the zipper stopped working along the way, so I ultimately bought a new jacket in town somewhere (Gatlinburg I think). I don't have a particular jacket to recommend to you, but something more durable than dri-ducks --- yes.
Synthetic/down mittens: I wonder how well these will work while on-trail? I'm not clear on exactly what you have in mind, but for those temps I would want the best handwear combo I could get. For me it would be very thin, light liner gloves, Dachstein wool mittens, and some sort of light shell big enough to fit the mittens (My eVent mittens were barely enough for the Dachsteins, a good combo). Don't cheap out on covering your extemities.
The Alpine Light down parka is an excellent piece of kit; in single digits with comforter wrapped around you maybe that will be okay, but the whole "drafts" thing makes me wonder. Generally you'll either be in sleeping mode, or you'll be "doing something", and I wonder if activity will allow the comforter to really help as much as you hope. I did most things "half in the bag" --- not half drunk, but with my lower body in my 20F sleeping bag, and the parka plus thermawrap vest inside that on my upper body.
Head protection: do bring a balaclava, the type that covers your nose. At least for me, my nose gets painfully cold at such temps otherwise. Then layer it under something warmer. What I used was a thick fleece hat sized to fit comfortably over the balaclava. That way I could use the fleece hat over my baseball type hat in the mornings, taking it off if/when I warmed up enough and putting it in my pocket as I walked.
There are so many alternative pieces of gear that I think it's unlikely that anyone can tell you what's adequate for you personally --- your 'style', your metabolism, your specific gear mix. Put together your first cut at gear and definitely try it out in conditions as close as possible to the most severe you think you'll likely encounter, certainly to include sleeping in such conditions. In a situation where it's easy to bail if things aren't working out!