There is a very small difference in chain length because of the different angles, but it's no more than you get from the lack of roundness with many 'circular' chainrings, particularly in that case where the chainstays are long and the size difference between chainring and sprocket is small.
No.
Always has half the teeth engaged.
There is a very small difference in chain length because of the different angles, but it's no more than you get from the lack of roundness with many 'circular' chainrings, particularly in that case where the chainstays are long and the size difference between chainring and sprocket is small.