by mfaulk80
Don't teach them every detail from the start. For example, I don't explain the specifics on battles until the first Ancient is attacked (or someone is contemplating it). I also avoid explaining every single tech, and opt for explaining as they come out if people have questions.Most of the RotA stuff is easy to add. You could leave out the Rare Techs, etc., but they're also not that big of a deal to throw in. It may help prevent someone from dominating with PMs since new players are a bit more susceptible to PMs imo.
I'd take out any of the special hexes (i.e. Ancient Hives, Supernova, etc.). Probably not a bad idea to throw in the two Ancient Homeworlds to balance the play area for 7. I'd also help anyone that looks in danger of being locked out of the center hexes. That's a little more likely to happen with the 7-9 player setup.
I honestly suggest that EVERYONE play with Terran. I know you want to explore the other races, but it's easier if everyone is playing the same. If not, then I'd pick a race with a bit subtler abilities such as Mechanema.