The entire set of NOAA charts, in raster format which work with SeaClear, are available for free from the NOAA website. There are some folks selling CDs of these as well on EBay, etc. for a few bucks along with other public domain documents like pilots. I originally bought one of these for $15. Well worth the money because my old dial-up service would have taken 2 1/2 years to download all those charts. They are also nicely filed and accessible.
As far as your hardware connection goes, they all have their own little problems. As I mentioned above, make sure you specify "Garmin USB" protocol when you select the GPS. My version of SeaClear works with no problems with both Garmin GPS units but I can remember having to wrestle with Open CPN and Sailcruiser. You just need to fiddle around until you get the right configuration with your hardware. Make sure your computer is seeing the GPS before even trying to use it with the software. You may need to download the latest driver that will work on your machine.
Alberg 35: With a philosophical flourish Cato throws himself upon his sword; I quietly take to the ship.