Sleep is key in the backcountry. If you're not sleeping well at night then you're not going to have a good time the following day or days.
Down vs. Synthetic
Down is super light weight and warm, and it gets that warmth from the loft or "puffy" nature of the feathers. Synthetic bags are a bit heavier, don't compress as well, but are great when the weather turns wet.
The downside of down is that if it gets wet, the loft goes away along with your warmth. If you're only camping when it's nice out (which is most people), then down will work great. If, for some reason, you like camping in the rain or know you're at risk of soaking your bag, you'll want to find a bag that has a synthetic fill.
Everyone knows what a sleeping bag is. My only advice here is to make sure that if you get a good old standard sleeping bag, that you make sure you fit it and that it's not too warm for what your needs are.
Get the best possible down you can get or if you're not a down person, find the best synthetic you can. No need to go crazy warm on the rating unless you know you'll need it.
This isn't your mothers quilt. This is something long distance hikers have been using for a long time. It's basically as sleeping bag without a zipper or a hood. You lay it on top of you versus getting in it.
There are a lot options out there and some people either love them or hate them. If you're looking to cut weight, hate the restricted feeling of a bag, and want more of a blanket feel, you might be suited for a quilt.
I'm currently testing one out in the summer of 2018.
Here's what you need to know about sleeping pads; while they may be comfortable to sleep on, they're actually built to insulate your body from the cold ground. When choosing a sleeping pad, you'll want to consider the shape, the weight it can hold without risking puncture, and if you want it to be insulated or not.