Unfortunately, there is simply no way of knowing the answer to the first question. Knowing which members of the SS, SA, Gestapo, Wehrmacht, Nazi Party, etc. were involved is impossible. While most claimed not to have taken part, most did. However, some didn't. Furthermore, it is almost impossible to determine where perpetration begins and bystander ends in many cases. Is the Police Battalion serviceman who refuses to shoot Jews but does guard Jews a perpetrator?

As to your second question, both the Western Allies and the USSR subjected their portions of occupied Germany to de-nazification. In this process, there were 5 categories into which a person could be placed: Major offenders, offenders, lesser offenders, followers, and exonerated. Depending on the category, the person would receive a punishment which could range from the death penalty (only in a relative few cases) to being given a status of "rehabilitated."

Here is a good answer by u/phoenixbasileus.