Does the track need to be exactly level?
I live in an old house, where the ceiling above the bay is not level left to right across the window, or from the front to back of the recess.
How important is it that the track is level? Ideally I want it inside the recess and flush with the ceiling.
Also, what is the smallest radius corner you can bend to? I want the curtains to hang as close to the corner as possible.
The tightest radius this track can bend is about 10cm. As to fixing to an unlevel ceiling. I do it quite often. The only slight problem comes when you come to hang the curtains.
If you are hanging floor length curtains you may have them hanging just off the floor in some places. Then draping a little on the floor in other places.
This also applies if your curtains are to hang to the window sill. It can be better to hang curtains that are either past the window sill but not too the floor. This way the uneven hem line is not so obvious.
The second option is when having long curtains Have slightly over long curtains, these break on to the floor between 1 to 5cm. This is very good for disguising uneven tracks or uneven floors. This can give your curtains a luxurious look.
Having said all that when fitting curtains in older houses. nothing is usually level not the floor or the ceiling. So it is all about doing the best you can to minimise the issue.
As to hanging close to the corners. I would need to see a photo of your bay window. Then I can get a better idea of what would work best. You can use the contact form to send me a photo.
Hope that helps.
All the best Lee