Underbody paint advice needed

So i am pretty much ready to spray the underside of car with colour matched Raptor liner however have a few questions:
-Obviously the rear of car is simple to figure out where to stop the underbody protection, with the front where did you guys underbody coat to? I am thinking stopping under the fire wall seam, spraying the rails and all inner fender (back of the shock towers) as well as back of the fenders. Maybe stop at the lowest point of rad support as well?
-The raptor liner is thick, for example where the leaf brackets and other items bolt on did you still coat or? Would it make bolting brackets back on difficult or will it simply crush the paint? Does it make installing rubber grommets a pain etc
-I will put greece in the bolt holes to avoid filling with paint
-Do i need to scuff up the primer or can i just spray Raptor straight over?
-The whole car was sand blasted any particular areas under the car that should be seam sealed? Wheel tubs already done!
-Should i also spray anything in the rails etc or dont bother? If so what products did you use?

Diff and all brackets will be dropped as well as the entire k frame and front end