is it legal to have the air intake (for heater and ac) coming from outside in CA?
Yes it is actually required for the combustion air. As for as the make up air or fresh air intake most newer homes do need them because the homes are sealed so tight that the build up of Co2 inside (from breathing) can reach unhealthy levels.
As far as the location that is not as tightly regulated so the person installing the system puts them as close to the system as possible to save $.