I think he is talking about server hoppers, basically. Like you connect to "SNIPER RIFLES EVERYWHERE" server and after that you connect to "genuine" one with all that top stuff...
Didn't found any suggestions about Hordes Event. Basically, it's just a spawn of 10-100+ zombies that moves through/near a town/village. Not a special thing to implement and will increase the atmosphere. So, what do everyone think?