you should work with the xfer center at your CCC and also talk to the UC rep when the visit.
In general, though, UC admissions are not formula driven. Your recent coursework will be taken to be more indicative of you than a class you took in 2015.
Yes, this works. The rules are kinda incomplete on the website but you can start with http://admission.universityofcalifornia.edu/counselors/q-and-a/repeating/index.html This question is an example of why you should work with your xfer center and the UC rep; the trick is going to be finding a course they will consider equivalent and there may be other technicalities