In reverse order...

Caldera cones are fitted to specific pots. Blacklite is heavy - if you are using alcohol stoves to cut weight you need to look at that pot too. The .9L Evernew (also sold at REI rebranded) is an excellent all purpose pot, not too large or too small, and not as expensive as many... I ordered a Caldera that fit it. Calderas come with a 12-10 alcohol stove that's very efficient and effective. Not all alcohol stoves work well with a caldera but I have also used a Packafeather with good results.

Tarptents are very good, high quality, but not for everyone. Most are not freestanding. Six Moons and similar cottage gear makers will not have samples in stores for you to play with, but they are for the most part good about working with you to make you happy - many have good return policies and excellent customer service. I'm always happy to mention Gossamer Gear, they are so responsive and go above and beyond to stand behind their products.

BA insulated air core is a three season pad. For a true standalone four season (in other words, you don't have to add a foam pad in snow) look at Exped 7 or 9 - expensive and heavy, but comfortable and having the highest R Value around.

http://sectionhiker.com/sleeping-pad-r-values/

I have a NeoAir and am quite happy with it - only con is having a 20 inch wide pad, but most of them are 20 inches wide, so ...

Another pad option is the Kooka Bay sleeping/air mattresses, I am thinking of having one made for me that is 66" long but 24 or 25 inches wide. They are light and inflatable, and get very good reviews from folks who get them. This is another cottage gear maker, so again, not in stores.

Lastly... down will pack smaller, and be lighter, than synthetic. Also it will last longer if you care for it properly - don't leave it compressed for weeks and months on end, wash/clean when needed (if used often like mine are, once a year suffices, especially if you don't climb in with filthy clothes on). I know folks with 20+ year old down bags.

Higher quality down will pack smaller and be warmer than an equal quantity of lower quality down, IE a 850fp down bag will require less down to keep one warm in freezing temps than a 650 fp bag.

And for further consideration....

Consider the Western Mountaineering Megalite: 30° F bag that weighs 1 lb 7 oz. Stuff sack size 6 x 12. Fill weight of 11 oz. 850 plus fp goose down.

Then there is the Marmot Trestles, a fairly decent brand for a bag, with a rating of 30F, synthetic and weighing in at 3 lbs 3 oz. Stuff sack size 7.5 x 16

Then there is the Marmot Hydrogen 30F down bag, weighing 1 lb 9 oz. Only one ounce different than the Megalite - but I would buy the Megalite. The slight weight difference is in the fill. Both are stuffed with 850fp down. The pricing is fairly close. Stuff sack size, 6 x 12 inches.

Then we have the Marmot Neverwinter 30F down bag at 1 lbs, 15 oz. with 600fp down. It takes 12 oz of 600fp down to get 30f rating, whereas with the 850fp down it takes 11 oz of down. Stuff sack size, 8.8 x 18 inches.

Differences are in the ounces between down bags, but the difference between synthetic and down is pretty plain. And Western Mountaineering is usually one of the first mentioned brands when quality and warmth are a priority for a reason - they really are well made bags, conservatively rated, usually warmer than advertised.

The other consideration -- your priorities. If you are a serious backpacker with intention of going out frequently and for years to come, down would be the ticket. If you are more concerned about budget and not so much about weight and size of the packed bag in the pack, or are not going to be backpacking a lot in the future, the Trestles is 89.00 full retail at REI, while the other bags are upward of $300.

Another option (which is the road I have taken) are quilts. Some folks are quite comfortable with them. I've been into the low 20F range with a down backpacking quilt from Jacks R Better. It weighs 1 lb, 4 oz and packs to the size of a softball.