Are bike lockers available

Plenty of these ...

According to their website Bicycle Lockers: Bicycle lockers have been installed by the San Diego Association of Governments (SANDAG) at San Diego International Airport. The lockers are FREE to use for bike commuters residing in San Diego County, but there is a $25.00 refundable key deposit, paid to SANDAG’s iCommute program, required to use them. In order to use these lockers, and other SANDAG bicycle lockers in the San Diego region, sign up here Lockers are available on a first-come, first-served basis. Bicycle lockers at the airport are located: East of the Terminal 1 pedestrian bridge, along the fence line (4 bikes) South of pet relief area at T2W, adjacent to northeast corner of NTC parking lot

I m not sure but most airport do have them bur some airports you have to be a club member to use them

Yes.