Eddie - I'm assuming you are using an HVLP sprayer.

Are you using the recommended tip size - usually a 3 for primer?

Is the pressure set to deliver the recommended psi WITH the trigger pulled AND being read at the gun. You don't need or want a glossy finish on the primer. Light coats after each tacks up would be much better.

As for the depressions, yes probably soft backing on sand paper. Use a hard back and diagonal cross patterns. Everything shows up once painted! As you are finding out.

Also, if you spray for prolonged periods the air in the hose gets hot which contributes to runs - shorter intervals and/or a bigger tank work better.

If you don't have a water separator and/or filter drier - you need one. If your gun starts spurting out water droplets in the paint you will be doing it over (can look a bit like orange peel too).

Once you are set up, go get a big piece of shiny cheap hardboard at the Home Depot aviation store and practice on that till you get the psi and pattern right (should be shaped like a semi fat cigar) and gun movement speed right to avoid drips. Thinner, 1/2 overlapping coats are always better for primer - it just needs to be built up to an even thickness so you can sand smooth to like 600 grit for color. Hardboard will act similarly to gelcoat.

Paint is an ARTTT = Aggravating Results Two or Three Times! Once you get it down though you'll be fine!

Greg