I will be attending NTC with a Battery + ADA unit in the near future (as their BN CBRN NCO). What should I prepare for CBRN wise?

Is it for a unit rotation? If so, it will be for 21 days (14 days of actual training with seven days of pre & post rotation stuff).

As a former executive officer for the OPFOR, I can tell you that you can expect to spend a great deal of time, most typically during the battle period, in MOPP4. The OPFOR has chemical weapons at its disposal and almost always deploys it; significantly retarding BlueFOR operations and attriting combat power. During warmer weather, this posture has obvious heat-related consequences on personnel.
Best of luck.
For Donovia!