To get the Locus helmet you needed to pre-order through MightyApe.co.nz. Or now you can go through the difficult task of going to a bunch of 7-11s and scanning codes or something.
The Fotus Armor set comes with the Halo 4 console.
At this point there are 10 Halo 4 maps. Over the next while though they will be releasing 9 additional maps in sets of 3.
Hope that helps.