I dont know for sure if the Rx_Mutator_Veterancy_x32 still works, you can load that mutator by adding the option below to your command-line. In the root folder of the SDK are files that you can use as an example, you can remove the "server-part" out of the command when you only play single-player.
mutators=Rx_Mutator_Veterancy_x32.Rx_Mutator_Veterancy_x32
I always start them by change the launcher file, mutators that do work for multiplayer will also work in single-player games.
No, you dont need to know what map youre gonna play, you justs load the mutator before/while you start the game.
You can setup mutators so they only work on some specific maps, but mostly they are not, i know only 2 mutators that are like this.
Smarter, aggressive.... i dont think so :).
Maybe you make them a lot stronger by changing the weapons.
I had the same feeling after i did write this mutator, but on that moment it did work.