To answer another part of the question...
RDD is heavily restricted. I think one must be epic to even be considered for RDD, and the CDQ required would be insanely tough. Not impossible, but hard enough that most people won't just say, "yeah, I'll try that....might be fun".
The Assassin PrC is restricted because the Evil alignment is restricted. To become an Assassin, you must first become Evil. To become evil, you have to fulfill certain requirements and convince the GM team that you can handle it within the boundaries of Layonara.
There's more, but as I said, all of this is available.