No! I am not taking the labs for the grade. As partners, I was the math guy in the lab, always doing the reports, post lab questions etc. My partners on the other hand did most of the practical hands on work. While I did partake in that, I deemed it as not so important ( I WAS SO WRONG! ). My primary reason for doing the labs is just getting on that hands on experience so that I am not sloppy when I join the research lab.
I was also a nontraditional applicant to medical school, and worked as a paid full time lab tech for 5 years before med school, with a 1.5 year break in the middle to do an undergrad postbac program so I could apply to medical school (I also took a few CC classes at night before decided to do a postbac full time)
I just finished med school and will be starting residency in July.
I think your plan is bad and you are approaching this wrong.
1. you are not going to learn anything more or gain any extra skills by auditing the gen chem class. This is intro chemistry stuff that is very basic and there is nothing "greater" to learn from it.
2. don't retake the chemistry lab. Again, this is entry level stuff and there is not much to learn. Any skills you need for the research job will be taught when you start. You will not gain any skills in the gen chem lab that will be very helpful in your research gig.
In my opinion, seeing as you are already mid-30s (?) and your plan is to go to medical school, you should be figuring out how you can finish your undergrad degree in as little time as possible. Medical schools already do not take many applicants in their 30s, and it seems like you will be closer to your 40s by the time you're applying. Furthermore, I think it will be more difficult to match into residency programs the older you are (mid 40s?).
Good luck with whatever you choose.