I've set my server to auto download but when friends try to connect it just tells them the maps missing it won't download it. Any tips?

Does anyone know if it's possible to have the script generate a random number between 2 numbers? i.e. set r1 "seta random 5" basically I have a list of maps rotating though but want it to start at a random map each time. Also is there a way to use the rcon command in the game to go to the ...