Hi, I will be flying from krakow to san francisco with a 50 minutes connection in Berlin Tegel Airport. I will be switching airlines, from Berlin Air to American Airlines. May I ask if I have to go through customs? If I have to go through customs, is the transfer time too short or alright and what are your experience with this airport custom? (How long to process and queue at the custom)

Another question is if I am switching to a different airline, do I have to collect my luggage or will it be transferred automatically? And how do I find out if I have to switch terminals or just the same terminal but a different gate number?

Thank you