Where are you located? I see the craigslist ad is near Columbia, SC. If you are in that area there is a relatively active group of catamaran sailors that sail on Murray, Wateree, and Keowee. You can see their schedule here:
http://www.emsa-sailing.org/schedule/I'd try to get in touch with them. They aren't all necessarily hobie sailors, but there are a lot of experienced and friendly catamaran guys their that I feel sure would be willing to help you out with learning to sail or finding a nice boat. There is also the Columbia Sailing Club located on Lake Murray.
I'm located in NC and typically sail on Lake Waccamaw. I'm also a member of the sailing club there. It's about 2 1/2 hours from Columbia, but I'd be happy to take you out on my 16 if you wanted to make the trip one weekend. The winds are usually pretty good there, so you could get an idea of what you'd be in for with a Hobie 16. We also have open Portsmouth racing at the club every 4th Saturday and we are hosting our annual Indian Summer Regatta October 8-9 which is open to all catamarans and shallow draft keel boats. Just shoot me a pm if you're interested.
As far as a Hobie 16 being your first boat, I'd say it can be done... but be prepared for a huge learning curve. I speak from experience here. I bought mine with virtually no sailing experience and no real mentors other than the internet in 2002 or so. There were many frustrating days trying to figure out how to rig the boat correctly, days when figuring out how to make a catamaran tack completely eluded me, windy days when I just couldn't keep the pointy end up, and confusion as to how the boat responded when things needed to happen fast. Not only are 16's much faster than most comparable sized mono hulls, the response time required to make adjustments is also significantly faster. Add in waves and currents and that's a whole other ballgame. It took me several years before I could finally say I felt comfortable sailing her in the majority of conditions I could expect to find. My learning grew exponentially when I finally met some friendly cat sailors that were really generous in sharing their knowledge a few years into learning, and I started showing up at regattas.
I don't write any of this to discourage you, as I loved every minute of working out the kinks with my 16. The hobie 16 is a great teacher, but she'll give you your licks while doing it.