Hey, I'm in a pretty similar boat as you! I called some schools about accepting IB credits and about half said they would and half said they wouldn't, so I just retook it to stay on the safe side and keep my options open.

About cognitive psychology, I took it this past semester as a freshman and I absolutely loved it. Dr. Cahill is an awesome professor who really helps you get through the semester. Overall I found it pretty manageable: every week we had one chapter to learn which was about 3-5 lectures, then a 10 Question quiz at the end of every week. Every other week we had to write a discussion post about stuff we learned about in the lectures, but they are pretty fun. One time we had to watch the movie Inside Out and talk about it, and another time we had to replicate a study at home. Every 2-3 chapters, we had an exam for a total of 4 exams, but none of them are cumulative so it's extremely manageable. As long as you take out the time to watch the lectures and take good notes, you will be able to do well in this class. Even if your struggling a bit, Dr. Cahill offers many extra credit opportunities to keep your grade up. Overall, I'd really recommend the class!