Additionally, how difficult is it to teach oneself pre-calc/calc? I'm assuming that I will need to take a college course from pre-calc on?

The real reason for relearning math is that I have an interest in learning physics (and I feel so embarrassingly humbled saying this here), perhaps with the goal of teaching elementary or secondary ed math or science (undergrad and grad work were in psychology and philosophy).

But let's start with the math :). Thanks.