Retaking Calculus, GPA, and Other Delights

I took Calculus senior year as a community college class taught on campus at my high school. Second semester, I really slacked off, and I ended up with a C+. First semester gives credit for math 20A, and second semester gives credit for 20B. My questions are as follows:
If I retake calculus at UCSD, will my high school calculus still effect my gpa? Will I still get some form of credit for it, even if it’s elective credit? Will I need to take the math placement exam because I’m not getting calculus credit? If I don’t retake calculus, or only take 20B at UCSD, will my transfer credits affect my gpa?

Thank you so much in advance to all who help.

Your community college course grades are separate and will not be included in your UCSD GPA. Since you passed both semesters, you should get credit for both Math 20A and 20B and should not have to take the placement test. It would be helpful to verify this information with UCSD’s Registar or address it during your orientation with your advisor.