Is there a way to set the tail number and call sign to be the same for every plane? I'd rather avoid going to ATC Options and setting it each time. I have a specific number and call sign I like to use, as it helps me stay aware when ATC speaking to me. 

Only on the basic package planes. You can edit the .cfg files (search the forum for how) and add it. All the planes from Premium and Deluxe are encrypted and the aircraft.cfg file is not available.