How hard is it to replace AC compressor

At a shop , with ALL the proper equipment , probably not to bad. On your own , in a driveway , (also , not knowing your experience level) , probably not something you'd want to try. Need to be able to properly recover and vacuum the system and then charge it with the correct amount of refrigerant , along with thorough evaluation of system , BEFORE repairs are done , so as not to waste money on a compressor , if the old one grenaded internally spewing debris into the entire system.