Regarding drilling round holes with a drill bit instead of a Unibit, (at
least in sheet metal), here's something I learned from an old lab tech years
ago. Works best on a drill press for larger bits but can work with a
hand-held if you're careful.

First, briefly run the drill bit in reverse when you first apply it to the
center punch spot, it'll form a nice starting dimple with little tendency
for the tip to wander. Next, lift the bit from the work-piece and put a
small patch of a standard red shop rag (about 1 or 2 inches square) over the
spot and finish drilling the hole. For some reason, instead of the standard
figure 8 hole, it'll be nice and round. I have no idea why this works but it
does.

Dan Schaefer