1. No don’t retake a class that is over a decade old.
2. You likely will need biochemistry in lieu of a second semester of organic chemistry. Some programs have additional requirements like stats, genetics, anatomy, but there aren’t many of them. Just something to be aware of. Likely you will be fine to apply for DO but MD may be tougher depending on where your gpa ends up.
3. Mcat prep should be after completing your prereqs, not before. If summer classes put you in a better position to do this then go for it. Right now, your timeline looks like you will be ready for the 2023 cycle as there isn’t much time between finishing your spring 2022 semester, needing to take and perform well on the MCAT, and prepare and submit polished applications to make the 2022 cycle.