What kind of snail is this? We can't be sure from the pictures, but it looks like a type of Apple snail called a Mystery snail (pomacea difusa/bridgesii) which are very common in the aquarium trade. For positive confirmation we would need 2 additional photographs: 1) one looking straight at the 'spiral' area, and 2) another of the spiral area looking at it from the side.
Or you can look for yourself at these sites at applesnail.net:
Apple snail (Ampullariidae) genera and species.
Applesnail.net • View topic - Species Photo Documentation
Do I need two of them to breed? Yes, you need a male and a female. However, you may have a female that was impregnated by a male before you got her.
What is that thing haning from the end of the snail?? The stringy white thing visible in the second photograph is, as absolutangel04 said, snail poop. However, if you meant the flat circular disk at the end of the fleshy part of the snail body, that is a "trapdoor" or operculum.
By the way, if anyone thinks their mystery snail is dead because it hasn't moved for 24, 48, 72 hours, please don't throw it out. Long periods of inactivity are normal for mystery snails. Pick it up and smell it. If it doesn't smell absolutely horrible, then it's still alive,