#1) Can't help you with that. A couple more posts on here and you may find the info. I think it's on the facebook group, too.
#2) I believe each of them are individual releases / versions. As to the exact definition of them and their contents, I am not sure. Even on the post where you got those I stated that I was hoping someone could describe them, one day
#3) I have not seen anyone post the classes and races. I created them for my board and packaged it into a megamud install that did it all for my users. I have attached the classes and races file from that. These would/should be placed into the folder for the BBS (e.g. Megamud\BBS\bbs_name). I suppose it could work going into the default too if the megamud instance is only going to be mudrev. Not sure if that would have any negative effects or not.
Let us know if it works.