guys,
i prepared my car underneath for spraying the black stuf insulation( i do not know how exactly to name it correctly ).
the new stuf i want to use is Teroson record 2000.
i need some help.

i decrease it as i could with nitro thiner. is it enouth? i must use any decreaser?

i see spots underneath the car that has only paint without that black insulation. should i spray new insulation all over the place or just were it was only?

should i paint the wheel wels after that black stuff or leave it as is?


also i removed the fenders and there is no black stuf there . only a somekind of primer maybe? (what it is?)
can anyone please suggest what to do with that areas that are painted only?( painted with what? primer? anticorosive metal paint?)
can i simply spray anticorosive paint only or shoot a car collor on top?
or what?

thanks!