T-track is a PITA: If you can't use the pre-drilled holes you are left trying to countersink any new holes you do drill, through the narrow slot in the top of the track (see an older thread of mine, somewhere). I ended up with a long strip of emery cloth and the drill press, reducing the diameter of a not-hardened cheapo countersink, so it would fit. In retrospect (as suggested at the time) I might have done better by regrinding a jobber drill to the right angle (for aluminium, I'd probably also need to ease off the relief angle, too, to stop it digging in).
On the piano hinges thing, clamp it down with a sacrificial bit of material - something like aluminium bar stock. Locate the hinge under the quill using an offset peg (to fit one of the other holes), so you can drill through "blind" but accurately. At best it will need a jig, and you might need lubrication to minimise chatter, and the right speed too.
I've got some cheap piano hinge I've used for tool boxes, and it's horrid stuff: thinly-chromed steel that's difficult to cut neatly and which rusts if you stare at it hard. It wouldn't be possible to countersink screws into it, either, as the steel is just too thin. Thankfully, for my application (somewhat "agricultural") it doesn't really matter, but I can't imagine another use for it - would look rather nasty on furniture, for example.
Almost forgot: My "universal" solution for improving the finish of holes in metalwork is Trefolex cutting compound. One tin will last you a lifetime, but that combined with some decent Dormer or SKF jobber drills (and drilling into something like a hardwood block underneath (sacrificial - make a fresh hole every time), will make a big difference to the quality.
You might also drill upside-down, by which I mean go in from the back side of the hinge. This is because a jobber drill will tear thin metal upwards mostly, so the damage will otherwise be on the side you see, rather than against the wood when it's finally fitted. If you have to take a file to the burr, it's probably better to do it where scratches won't show. I'd try both, but not be surprised if neither gives a terribly nice result tho.