I bought a heat gun from Home Depot (paint dept.), I used a small paint scraper as a straight edge to flatten them straight. I had the gun on low and never got more than 4" close, keep the gun moving, it only takes a few seconds.
As for removing the inserts, I used a 13/64 drill bit. The rivets are aluminum and the bit never has to go through the grill so you never touch the plastic. When you start drilling, the aluminum just spirals away and before you go very far they just pop through. I drilled from the back. The two rivets closest to the metal back brace have to be drilled from the front and those are a little bit harder.
I'm still looking for the means to attach the inserts back but at the very least I have a friend of mine (he works in purchasing) looking for a black round head hex machine screw. I have some on a machine I use at work but obviously I can't take those. After I'm done you won't be able to tell the difference.
Finally, for the paint, I got the correct silver from Totally Auto, Inc. but the black I got from Murray's auto parts. It's the only "Satin Black" that I could find that I liked and was like the factory paint. I can't remember who makes it but I can find out if you want me to.