OOPS that second question should be:
Can I partition the nonce and have each core work on a subset?
Yeah, and also even to some extent you can vary nTime.
There seems to be one of two routes people are going with this. Either talk over USB to a host or have a complete standalone miner that hooks into your network with Ethernet. If you plan to go the later I would be happy to help package up the embedded software for it.
At this stage of things, you are going to want to use Stratum as the protocol to talk to pools.
https://docs.google.com/document/d/17zHy1SUlhgtCMbypO8cHgpWH73V5iUQKk_0rWvMqSNs/edit?hl=en_USI would look at
https://github.com/m0mchil/poclbm as an example miner as it is not GPLed, unlike the two linked too above. At least until you decide for sure if you want to deal with the GPL.