The stinger is models... for everything else you can get by for a while (ie there are free texture packs hanging around, Maplet will do you at least to begin with where levels are concerned) but models are the one area where you really are constrained by what you can either make or afford to buy. This is normally due to them being the one thing that need to be specific to your game rather than generic and it means being realistic about what assets are available before beginning a project (ie it's pointless to begin an FPS if you haven't secured a single space marine model).
As for the coding side of things. Well, I don't know much about how 3D programming works either - that's why I use Blitz :) Most of the mumbo gumbo (jumbo?) is stuff you won't need to worry about to begin with... I'd download the demo and get comfy moving things about and seeing if they've hit one another. That's the basis for all you'll do, everything else is icing.
As for the coding side of things. Well, I don't know much about how 3D programming works either - that's why I use Blitz :) Most of the mumbo gumbo (jumbo?) is stuff you won't need to worry about to begin with... I'd download the demo and get comfy moving things about and seeing if they've hit one another. That's the basis for all you'll do, everything else is icing.