so will i be able to pick weapons like the BR or DMR on the map when im level 1 or what ever the starting rank is???
You will have to unlock them for your own custom loadouts. Premade loadouts will be available, these may include the BR or DMR. The prefab loadouts are going to be tailored specifically per map.
In most game modes of Halo 4, I believe you can not pick up weapons on the map, unless they are from a fallen friend/foe.
But there are 2 pre-set loadouts, regardless of rank, made specifically for that map.
So, no. You will not be forced to use an AR on Exile because you don’t have the BR unlocked. It just depends if the designers saw that weapon appropriate for that map. You won’t find ARs in the pre-set loadout of Exile, but possibly on Adrift or Haven, since they are small maps.
Through preset loadouts, I believe you can.