How will passport and customs controls work (both in the outgoing and the incoming airports of the flight) on flights to/from Tijuana Airport (TIJ) when the new Cross Border Xpress terminal on the U.S. soil becomes fully functional  

How will it work for flights:

 - to/from Mexico airports, 
 - to/from US airports, 
 - to/from airports in other countries?

E.g. suppose I buy a ticket San-Francisco -> Tijuana. Do I have to go through the passport/customs controls in the SF airport if I intend to come out on the US side after arriving in Tijuana?  

Or can I choose when I have arrived to the TIJ airport whether I wish to remain in the US or to enter Mexico?  

What about going on flights like Cancun <-> Tijuana or Vancouver <-> Tijuana?