Maps and Experience

Is there a reason why Ravine, Impact and Erosion is out from maps rotations?
I am playing halo 4 only for two weeks and I never notice those maps until I visit the section “Maps” on the site and I discover that they are not in any current playlists in the section “Playlist” and I wonder why.

At the end of a game is it possibile to earn more than 750 in the section “points” (or performance, i do not know how is it in english) of the “experience gained” and at the end is it possibile to earn more than 2981XP in a match or not?

Thanks for the answers and sorry if these questions were posted before.

The 3 maps you mentioned are forge-only maps, designed for community creations, like a canvas for building a map on. as for the 750 performance bonus, i don’t think so. and as for the 2981xp, i often get more than that, but that may be due to pioneer (fasttrack) armour mod.