Maintaining Primed Paint?? (flat black)

[Twinkie]

Hey all, Ive tried searching but cant seem to find an answere...sorry if this was already covered...

Ive been thinking of doing body work on my car and priming it flat black myself before i take it to the paint shop. but i wouldnt be taking it to the paint shop anytime soon after i prime it. so.....

for you guys who have flat black prime, how do you deal with the annoying scratch marks ont he flat color (if scratch marks do ever appear)?? I would imagine since the primer is flat colored, a lot of marks would occur if things get rubbed up againts it like fingernails or your zipper on a sweater while your working under the hood (againts fenders and what not).
Also, will the prime be ruined in the rain/water during wintertime or the scortching hot sun in the summer time? Do you guys wash your car regularly with the black prime? if so, how do you wash it?

thanks guys.