That's and interesting piece, Almost seems to be fiberglass from the pic, Yes I would do more prime, (let that dry first, and fill those pinholes with glaze putty if you have access to it) if not, put a big wet puddle of primer on them, and then spray the whole thing again over your puddles and lightly block any problem areas , and bury again, you can get pretty close and put it on good and wet with that stuff and the runs will sand off later, you ultimately want smooth and flat at around the 400-1000 grit wet sand and cured/dried before you even think color.....If that's fiberglass the edges will always look like that, that a mold plug thing, unfinished edges and all, most of it will sand out with your primer, (don't go too deep) only sand on your primer Not into the substrate or you have to basically start over.