CoD has a second dvar that stores your current rotation and would then load the next one from sv_maprotation once it finishes it. All fastApply does is to reset this dvar so its empty and the next map is from your new rotation.

PlayerCountOverrides is used if you want to override the player counts where the map pools are switched for example on a 64 players CoD 4 server.

No worries, I was pretty confident that its not my plug-in in the latest version anyways.

Thats because a manually installed version takes preference over the plug-in store version.