You could also use the World Vector Shorelines (http://shoreline.noaa.gov/data/datasheets/wvs.html) or if you need lakes, the GSHHG (http://www.ngdc.noaa.gov/mgg/shorelines/gshhs.html) from NOAA.

I recently implemented similar functionality in Python, I haven't open sourced it (yet) but I can share some code if you want.

I have anecdotal evidence that pursuing a full CS degree is not necessary to find a programming job but what might help is following some offline (official) lessons as my girlfriend did or getting certified in a technology you want to work with. So my advice would be to keep searching for a job and to continue learning and make your efforts visible (blog, github, etc.). Bonus tip: add some contact information to your web profiles like this one on hn.

I'm from Europe (Belgium) so I can't really comment on the situation in the USA. But we have here a continuous need for good GIS programmers for government contract work but also for utility organisations and some larger businesses. Also things like track-and-trace are booming. I never regretted getting in this business although I must admit that I came from the opposite direction (from a master in geography to fulltime programming).