In a couple of weeks, I'll be flying a three-leg trip from EU to US via FRA and IAD (FRA-IAD-US on UA flights) in Polaris.

It's my first time on UA business class.
1) What lounge do you recommend in FRA?
2) What amenities need to be asked for on the flight FRA-IAD (e.g. mattress pad, noise cancelling headphones, etc.)?
3) Anything that you recommend for a nicer experience?
4) I have a 3.5 hour connection at IAD. I'm planning to visit the Polaris Lounge. I understand there's a dining room - is this an extra fee service?