I've done this flight a few times in both Y and C...
1. Yes, C is much better than Y...but the Y exit row is fine for me as I don't have an American-sized backside.
2. With a C seat and no status, you will get access to the T4 Skyview lounge in JFK (which also doubles as the NW WorldClub) and the RCC in FRA.
3. This is not an american airline. Alcohol is free. See the menus threads for sample drink menus in both classes.
4. You will get the configurations with row 39 as the exit row.
5. For me, yes.