Jennifer, I think you're narrowing your potential market too much by focussing on trackdays - I don't do them, but I do like getting footage of various runs, and I know a lot of bikers round my way who do the same. Currently I use a Veho Muvi mini camera as it was cheap, lightweight and came with a lot of fixing options.
What do I want from a camera? Good quality video, maybe not full HD but watchable on a standard telly, light weight, good battery life and recording time, variety of mounting options (all those you mention and more - the tank f'rinstance), vibration damping, good sound filtering (ever heard the wind rush at even 60mph?) and controls that can be used by someone wearing bike gloves. How hard can it be?
Here's some footage shot with the Muvi strapped to my offside mirror - this has vibration dampeners, the mirror is clear but look at the video quality, and listen to the windrush.....
That should give you something to think about for now ...