I'm going to put forward some possible interest in this. And since you said the points were up for discussion, I'll give my opinion on them.

1. I like it; it's a nice change from the typical norm of the human race being either the newcomers or the underdogs. 

2. My opinion on the matter of psionics and the like is that it should be allowed, but it shouldn't be overpowered and a sort of 'sci-fi' magic that can beat technology every time. After all, psionics can provide for some rather interesting nations and races (so long as nobody tries to use psionics as a justification for an entire overpowered race of beings). You could have races that come have it naturally, and perhaps look down on those who can only achieve it through genetic and cybernetic modification or something. Just a thought, since right now I'm just vomiting my thoughts out onto this post.

3. I agree completely. When your imagination's the limit, the galaxy shouldn't be full of rubber-forehead aliens unless there's a reason for it.

4. Once again, complete agreement.

5. Cool.