Divot repair in laminate flooring
Sounds like a workable way to make a repair, but the circle is going to be visible for sure, and is that really better than having the divot to begin with?  That's up to you...  Assuming this is what you want to do:


  Do the plugs and drill holes match?


A plug cutter labeled 1/2" will cut a hole that fits into the hole that a 1/2" drill bit creates.  A plug cutter is measured by the outside diameter of the plug, and a drill bit is measured by the inside diameter of the hole.  The caveat is that your drill bit may wobble and not make a great, tight hole.


  Will the plug sit flush...


Laminate flooring typically has some type of pad or underlayment or something between it and the subfloor.  So, you'll need to match the thickness of this underlayment (assuming you also tear out a hole of the underlayment when you drill) so the plug doesn't sit too low.  You can use this to your advantage and use layers of paper or something to make it sit exactly as high as you want.


  Will the edge chip


I don't think it will, but depends on the floor.  Some have a more vinyl-like top, and some have a more brittle wood-feeling texture. Put a flat object bigger than the diameter of the hole on top of the plug and hit that to press in the plug rather than hitting the plug directly.  This will drive it in as evenly as possible.


  Glue cause swelling


Don't use a polyurethane glue like "Gorilla glue" that expands as it drys and there shouldn't be an issue.  Wood glue is probably best - PVC glue is going to be super messy and will eat/discolor the surface layer almost immediately.


  will the drill skitter...


I like the plan of using the scrap plank.  Make sure it has a good tight hole in it.


  What drill bit


A hole saw in 1/2" might be hard to find, and probably wouldn't make a clean cut.  A brad point or Forstner is good but still might be hard depending on the underlayment and if there's a concrete subfloor.


  What could go wrong?


The hole you drill in the existing floor could be sloppy.  Then your only choice is to make a bigger hole and try to do it better.  Practice on scrap before hand.