You know how you ususally do a crumb coat or thin layer of buttercream on the cake before you ad fondant...Can I do the same thing with Rich's bettercream (or pastry pride) or is it not stiff enough?

When I asked this question, I was told no. From what I remember, the moisture in RBC gets soaked into your fondant making it soggy - or something like that. Maybe some can explain it better, but to answer your question, no, you can't put fondant on top of RBC or PP.

Do you think I can still use the Bettercream between the layers?

I wouldn't see why you can't use it between the layers as long as the fondant isn't on it. I would make my dam with BC and then fill with the RBC or PP....I'd be afraid of a blowout with out the dam, but I've never used RBC for filling so I'm just guessing here.