1. Nah, I didn't do as well in O-chem as I would have liked either(and I'm not some overachiever, I really sucked it up), but when you do your DAT studying, focus on that. I had similar neck of the wood grades in O-chem due to some family issues and laziness, similar stuff, but when I was studying for DATs absolutely went overboard on OC and GC. That way, when a teacher asked me about a class like O-chem that I had an issue with, I could point them in the direction of my DAT score and say, "hey, I had this prob, but I know the material." They'd say "wow, ok." And that was that. The DAT is your chance for redemption. It was for me.
2. Def not. I didn't take mine till late also (you do need some time to study), like August-ish I believe. I was a bit behind in the application process and some schools do have class-management issues (see my past posts for a rant or two on that topic if need be) but you should be ok taking them then. Just make sure to prepare adequately and def submit the rest of the app earlier and then just send in the DAT scores.
3. I think we're like long lost brothers, sans the finance. I also worked in the medical field while applying. I never felt it worked against me, and if I was asked why I said, "Hey, I had an in there and got paid well. What can I say?" More importantly, it can be ammo for you to use as to why you do NOT want to go into medicine (they love that ? in interviews). B/c only by being on both sides of the fence can one really say why they truly wanna go dent.
4. I took Kaplan course, and more importantly, I paid for it myself, with my graduation money. Along with wanting to get into school, the fact that that cash was my money that I could have spent on a nice trip to some sunny far off island, made me want to take advantage of the class and the studying all the much more and I took the whole thing a lot more seriously. It definitely helped me out in the long run. I studied mostly from Kaplan materials, and used Exam Krackers for o-chem and g-chem to supplement for those areas. Old text books were helpful for illustrations here and there and helping go over the finer points of topics. I would also highly suggest taking a practice test timed every day for a week before the real thing. It really gets you in the mode. A bunch of my classmates and I did that strategy and seeing they are my classmates it seems to have worked. Using only that and none of the gimmicky stuff people like to hock on here I dismantled the DAT, don't let people on here tell you you can't. Just study like crazy and be focused n you'll do fine.
Good luck!
-Pete