airberlin topbonus - Airberlin departure gates at FRA?

I know that AB operates out of T2 in the E area, but what level and what gates do they use? I'm connecting from AA (T2 D gates) and would like to know how far I need to walk bwtween AA arrival gate and AB departure gate. My AB flight out of FRA is to Spain. Will I need to pass thru immigration after arrival at FRA or can I proceed directly to AB departure gate? thanks!

You will need to pass through immigration in Frankfurt, but you do not need to reclaim your checked baggage there. You'll pick up your checked baggage at your Spanish destination.

Sorry, but I can't help as far as the question about the distance between gates is concerned.

The non-schengen gates and the schengen gates at FRA are on different levels. You'll have to clear immigration there and get to your gate. AB operates from D gates as well.