hey
usually you will need to prime over bare metal other wise you will get so called 'fish eye' , usually goes sorta wrinkly around the bare metal if you dont prime properly . depending on what kind of quality your after i would recommend go to the paint shop and buy a product called barcode , which you spray over the primer to seal the metal and prevent it from getting that fish eye.
on the other side i wouldnt bother with acrylic , yeah its good for amatures etc . iv used it on a few cars over the past , and i have to say its okay for a temporary fix , but itll never give you the finish you want, and by that i mean durability. acrylic can produce an amazing top end shine which is supposed to be better then 2 pak but no one does it these days as it takes hours to cut it back through the grades and compound cutter etc , but i warn you all it takes is a few splashes of petrol when your filling your car up , and its ruined. i did the rear on my r34 a year ago and had it dribble down , and ruined my mirror finish.
if its a car your going to keep for years to come , just suck it up and find a good cheap spray painter , and get them to blend it in properly .