I'd personally go with a 20 degree bag unless you're planning on doing hunts later in the season; they are for the most part quite a bit lighter and pack down a lot smaller. I use a Mountain Hardwear Ultra Lamina 20* and it's been great for the past 2 seasons. Kifaru's Slick 20 is a sweet bag, too.
Kif has updated their pack designs a LOT since the Siwash, I'd personally look around for a lightly used Duplex frame and a bag like the DT2, DT1, Mountain Warrior, or AMR. Their internal framed T2 and T1s are awesome packs too and can be found for cheap... Lots of options on packs though. Stone Glacier would be another I looked into.
I like the Thermarest Neo-Air pads with a closed cell pad under for a little extra insulation, but it's not 100% necessary in my opinion.
I use the First Lite Uncompahgre puffy jacket, packs down nice and tight and is extremely warm in my experience.
Hope that helps some.
Tanner
After reading the OPs initial inquiry, I was going to post, well, I was going to post what Tanner posted, to an item. Now, I'll just leave. You have good taste Tanner.
