I mostly second all of what Landon said. If you're used to a classical setup then your flamenco setup will be a bit lower, but it does indeed fall into a wide range. A lot of it has to do with how much resistance you want/need for your right hand (and if you like a lot of resistance, is it then too much for your left hand?) Also the lower you go the more buzz you're likely to get, so again it's about how much is too much and what's just right for you.
As for strings, I've always used LaBella classical strings. I feel like I hear the guitar and not the string with them, and also they're not very expensive :) Lately I've been using the Pepe Romero Jr. strings, which are made by LaBella but have different trebles than the 2001's I've played most of my life. I like a heavier tension string in general, but each guitar is different, so I have one guitar that needs light tension strings to feel like most guitars feel will heavy tension.
The good news is that experimenting with strings is fun, and you never know what might sound amazing on your particular guitar. (Also, don't assume that a really expensive set of strings is going to change your guitar's sound. It never really does...)
Having said all that, I'm curious to hear everyone's experience with strings. Let me know what you guys like or don't!