Unfortunately, I don't have any good resolution for these problems. It is often easier to discern the weak points of a mathematical or conceptual framework than it is to come up with something robust, especially since our intuitions aren't even necessarily self-consistent.

For instance, I think you're probably quite right that the discounting is different for people on different sides of an issue. Additionally, although there is presumably some truth to the matter of how big an impact past wrongs have on current conditions, it seems very doubtful that there is a robust way to calculate this, and even if one could calculate it, it seems very doubtful that there would be any way to provide it that effectively made it as if the harm had never happened. So the most literal approach of "just fix the problem" doesn't seem to me to be a practical solution.

Regarding men vs. all people, at the time the Declaration of Independence was written, "men" was the standard term for all people as well the term for men as opposed to women. In any case, regardless of the opinions of the founders (which were varied on many issues, incidentally), it has since been decided--forcefully and successfully argued by Frederick Douglass among others--that the appropriate sentiment to take is that all individuals are created equal, are endowed with freedom, and so on. So that question is answered.

You make a good point about class action lawsuits. That is a possible model, at least if we convince ourselves that class action lawsuits are an appropriate means to obtain justice. I haven't investigated the issue enough to have a strong opinion.

Regarding what to do instead of matching cruelty with cruelty to redress past wrongs, I'm not really sure how to handle this at all.

One idea is that in a just society that has compassion for all its members, the society will put those resources needed into members who are disadvantaged such that they will be able to have equally fulfilling, productive lives as those who didn't start out disadvantaged. In this case, the redress is not an explicit accounting of past wrongs, but a shared cost paid by society that fixes the lingering consequences.

The downside of this idea, however, is that unless you completely do away with the idea of individual property (and we have substantial evidence that this doesn't work on the scale of modern societies), the perpetrators of wrongs may well end up better off than if they hadn't perpetrated the wrongs. And that doesn't seem right.

I don't have a good resolution to this at this time.