If I want 3 rounds in an 18 minute span, does the game automatically do the division now?
Yes, the new create server menu asks for round count now, instead of round time. This makes sure when you play localhost servers you get the number of rounds you want without thinking too hard. It also takes into account the round delay so you get full timed rounds.
You can still use the ge_roundtime variable if you set the round count variable to -1.
But it the round count variable is > -1, it will automatically divide the rounds based on your desired count (0 and 1 are equivalent to each other, ie no rounds).