Thanks for the tips, and the good luck - I'm gunna bloody need it! lol!
My main concern is the terrible thought of completely screwing the game up, however, I heard that if you purchase through Steam you can simply uninstall and then reinstall the original - is that correct as far as you know?
When I get started on Galciv 3 I'm just going to pace myself, choose one of my planned out custom races and take it one mod at a time - first static art, then up the race traits points to 8 (I don't think 5 is enough), then ship designs and so on.
Thanks again for the info and I hope I can pick your brain again in future!