well it definitely sounds like a better solution than just running it through a straight guitar amp. if it sounds pretty damn decent to your ears as is then i'd run with it.
the most popular preamp out there is likely the Tech21 SansAmp. again though, if you're satisfied with the sound you're able to get now then i wouldn't worry too much about it until you're ready to upgrade to a beefier / higher quality sound rig / gigging (and paid) on a regular basis etc.
as for the distortion i would have asked to try out a handful of pedals once i knew the amp could handle a clean signal smoothly. i'd try the metal zone, a big muff, tube screamer, etc. maybe a couple of compressors or octavers as well. you never really know what will provide that magic tone until you hear it. just make sure to turn down all the knobs on the pedal before experimenting with it. when it comes to fuzz a lot of times less is WAY more unless you're going for some wall of sound / shoegaze action.