Tagging @Gumbymom as the resident CA publics expert.
In the meantime:
▸ Can my Advanced Placement exams be used to meet TAG requirements?
Yes. Units from AP exams can be used to meet the unit requirement for TAG. AP exams can also be used to meet subject requirements. Unit values and UC subject requirement areas can be found on the UC AP exam credits page.
Consult the UCSB general catalog AP chart for UCSB course equivalents.
I do know for 4 the answer is yes, you can apply to other schools at the same time as you apply for your TAG school.