Auto body repair & detailing: Primer and Fiberglass, urethane paint, dodge avenger

Question
Ken
I am working on a 98 Dodge Avenger and have installed a body kit.  I primed the car for paint in a urethane base primer as the paint job was to be in single stage urethane paint.  Now I'm told by my son that it's going to be basecoat/clear.  Is this urethane primer ok with base/clear?
Also, the front bumper to the body kit after being primed has hundreds of tiny pin holes in it.  Doesn't go through the bumper.  I first thought it was fisheye from spraying the primer in my garage but after sanding the primer off, the pin holes are still there.  The bumper was used and the old paint was stripped off(without chemicals).  I think there is a chemical reaction happening when I apply the primer, possibly the old paint is still in the pores of the fiberglass.
Is there an aerosol sealer I can apply before the primer.  I really don't have the money to buy a gal of sealer for 1 bumper.  NOTE:  This only happened on the bumper.  No reaction on the skirts or rear bumper.  Thanks for your advice.

Answer
Yes it is OK to apply base-coat clear-coat over urethane primer most clear-coats are in fact urethane. Just make sure your primer is dry and sanded or scuffed. As far as the bumper go's just put on wet coats of primer let dry sand and reapply primer until holes fill. sealer more than likely will not help this problem.
            Thank you for the question !
            Ken