Well, Forge World may not have new Tau for you right now, but the Games Workshop mothership does. For the Tau Codex can now be ordered, and along with it, some extras as well.
As I mentioned, you've got the Tau Codex now available to order. There's also a painting guide so that way you can know how to make your army look the best. Want it all? There's a bundle pack available as well.
In terms of models, you have to have Tau Empire Commander. Gotta have someone be in charge. How else can you coordinate the expansion of the Tau Empire without someone in control of it all?