The fps reported by Babylon.js is the fps of the whole frame, javascript + GPU. As the GPU runs in parallel to javascript, to run at 60fps, the javascript code must take less than 16.66ms, and the same for the GPU code.
So:
should not be possible. Do you have a repro so that we can have a look?
It can be possible if you look at “Absolute fps”, because this counter only takes into account javascript time. So, if javascript code takes less than 16.66ms, “Absolute fps” will report 60 or higher, even if GPU time is > 16.66ms.
As far as the number of draw calls is concerned, the fewer the better, but it’s impossible to give a hard limit, the performance will greatly depend on your CPU and GPU device.
I think this thread will help for your other questions: