I would not have bought RX480s, they're not really more powerful than the RX470s.
That said, I think ZEC will go back up once they fix their z wallet bug. Also, it's still more profitable to mine than ETH for the moment...
no, it is not.
Depends on your specific rigs and specific energy costs.
For *ME* right now ETH is more profitable - but it's close enough that could change tomorrow.
ETH last announcement I saw was middle of next year for POS - though 2 GB cards will get "DAG size killed" sometime sooner.