Have you ridden full-suspension bikes before? If not, have you ridden both XC and trail hardtails? Do you have an idea of what geometry you'd want? The FM909, FM936, and S3 that Schumo mentioned have great reviews, they're super light, fast, and aggressive. They are pretty progressive geometry, though, which can be good or bad depending on your preferences. They will have a longer reach, steeper seat tube angle, and slacker head tube angle than your average XC bike (although the newest name-brand XC bikes are starting to go that way too). I have an LCFS911 that I really really like. It's boost, moderately aggressive (kind of in between FM936 and typical old-school XC geo), and pretty light. It's maybe 100-300g heavier than some of the other XC frames, but mine came in at 23.2 lbs with a moderate build kit.
As far as the rear shock, just get a shock that matches the eye-to-eye and stroke that the frame takes. There's regular eyelet and trunnion mounting styles, too. I personally am a fan of Manitous, so I run a McLeod on one bike and Mara on the other. Most Chinese direct frames don't come with a shock, and I believe some may come with hardware. The hardware is usually listed on the specs page, for example my LCFS911 uses M8x22.2mm hardware, so just purchase hardware of that size.