IBJ centre :
refer to the diagram, IBJ (1) and IBJ (2) may be same and may be different. it depends upon your design of vehicle. it can be calculated easily if you know what angle your joint gonna make. and track width (rear) of your vehicle. CV joint have less maximum possible angle than universal joint and more the angle more will be the loss in rpm in each joint. if you want the exact calculation of loss in rpm due joint then you will have to do some research.
NHV – noise , vibration and harshness
basically its deals with the noise and vibration problem which is gonna rise due to the running engine. as vibration is considered to be very fatal for any structure and in this case the roll cage some of the vibration problem are fatigue stress induced in the roll cage , loosing of nut from bolts,…..noise is also very fatal but not from structure but for environment…. so the baja committe will ask you how you are going to reduce these problem. so there are many solution like padding the engine or harnessing the engine on spring, if you want the detailed calculation how much is gonna vibrate the you can calculate for calculation you have to read the FORCED VIBRATION chapter from any recommended engineering book but i think it is not necessary just give them the way to eliminate these problems mainly vibration.