Firstly: the local Forum Sherriff says welcome aboard, Tek. Enjoy your stay with us.
The GSB forums are thinly populated these days but we do also have a very good signal-to-noise ratio, and we strive to keep it that way. If you have additional questions, feel free to ask them.
Most of the forum activity these days is centered around the Gratuitous Modding subforum; drop by and take a good look around.
Oh, and fellow noob Redd13 has a very instructive thread going on right here which should be of considerable interest to all new players: Diary of a Space Tyrant.
You got it.
You can always re-use your original GSB download link over and over. If you buy the game directly from Positech (recommended!), the email which includes your special info is sent to you by BMT Micro. And if that link should ever become broken, cliffski (Cliff Harris: GSB’s developer and all-around cool dude) has repeatedly proven he’s more than happy to send you a new link.
Regarding your second point, technically what happens is that once you manually register your copy of GSB via your username & password, your game install will check-in with the Positech GSB server once every 24 hours. Should there be a patch available, it will be downloaded and installed automatically. This late in the game’s development cycle, patches are very rare but there is a new & slightly buggy one out there that’s just a few weeks old and which, itself, is possibly going to be repaired via a subsequent patch Real Soon Now™.