how do i add a intermission and teleporter and zombie waves?

how do i add a intermission and timer with it and it it to teleport to my map? and if they die they go to lobby and wait the timer and one more thing how do i create zombie waves with custom zombies? and the timer will be 30 seconds and the match will not end unless every body dies and if they do they go to lobby and if round over they go back in the match