You were gone ?
just kidding.
1.) Because the 'core' of the game is centered on carrier mode and missions were added as 'examples' other missions can be created by the community and added. Mod's kinda of make that difficult though because of conflicts.
2.) Less traffic ??? Okay if you say so, I found the amount of traffic to be so hight I installed the layers mod. Beerys work I believe.
3.) Ill remain mute on this subject as its kind of a hot potatoe. But there are a plethora of mods available. There is a whole forum section dedicated to them.