Ok. There are a few points that I think you need to be a bit more clear concerning.
1. The timing issue. If they EEOC believes that you failed to file with them within the 300 days, you really need to address that as fully as you can. I think though that this is just the employer making that allegation. Regardless, if you can establish which investigator you followed up with, that will help that issue.
2. You state that the infractions are related to your use of worker's compensation. That's not a bad point to make, but it detracts from your overall allegation that this is a race and age discrimination claim. It suggests that worker's compensation retaliation was really their motivation, which isn't a problem...it's just not something the EEOC deals with.
3. Good job specifically addressing certain allegations against you. Pointing out the discrimination within each allegation and giving an explanation for your actions is important. If you deny, outright, their allegations you create what is called a "material fact in dispute." Those issues have to go to a jury, meaning that you insulate yourself from a summary judgment during a lawsuit....which is important.
4. I have concerns about your explanation concerning not clocking out for lunch. If you chose to work through lunch to leave early, but also worked overtime, that actually means that you didn't leave early. That being said, you do make a good argument concerning previous overtime and not having any warnings in your files that you shouldn't work overtime.
5. I'm concerned about the argument that you were replaced by a white person, when they are stating that you were replaced by an older person of the same race. Yes, bring up that it was 7 months after you left, by a different manager, but even still it means that you can't insinuate that you were replaced by a white male.
6. They make the argument that they have no complaints from you to be able to claim a defense that they never got a chance to cure. Stating that you did complain and don't know why they have no record of it again creates an issue of fact, so it's a good position to point out.
Potential additional argument:
Most importantly, if you can point to other people that have worked through their lunch periods and worked overtime, that differ from you in race and age and were not fired, that helps to establish disparate treatment.