Is it possible to assign different pools (or coins) to specific GPUs in a rig?
For example, GPU1 for ETH pool and GPU2 for ETC pool.
Not in a single instance of the miner. The miner can only use one Ethereum based pool and one of the dual mode coins for all of the cards. However, you can specify which cards to use and then start a second miner instance to mine at a different pool for another card not being used in the first.