From a flavor point of view, I find rye to be fairly subtle, so even 50% rye wouldn't be excessive IMO. From a process point of view, rye is annoying to work with, but it can be beaten--a quick protein rest at 122-124F, some rice hulls, and a sparge temperature above 160F should solve it. So, I dunno, maybe 30% would be a good place to start (as long as it's malted, that is--unmalted rye is far more annoying to work with and contains no enzymes, whereas malted will convert itself; you could include a little unmalted flaked for character and head retention, though).
For hops, I would use whatever you like for an American IPA profile. I guess I personally would avoid the more "fruity" but non-citrus hops, such as Citra or Belma, and focus more on the pine/grapefruit/dank hops. But really, that describes most American hops, I think. Noble hops could work too and might be interesting.