1. I doupt most free ride bikes do(so they can climb), but a lot of true DHers run a single ring up front with a chain guide. Just depends on what a person wants to do with their rides. If you wanna climb your bike to the top downhills, you better have a granny or like walking a bike.
2. FSR is a Specialized trademark name for their 4bar full suspension design. No idea what it actually means, but if you really care, go to their website.