AS White Light FringesWatch
But, surely, for the white light fringes it's not coherent, due to the nature of white light.
1) Does this mean that predictable and repeatable interference patterns can be expected, when white light is diffracted through a single/double slit?
2) And, if the white light isn't coherent, how does interference even happen?
The red diffracts, the green diffracts, the blue diffracts etc etc.
You can consider each specific wavelength as diffracting independently of the others. Each diffracts a slightly different amount, giving the characteristic rainbow pattern.
This is a diffraction grating pattern but the principle is the same.
Monochromatic green at the top, white below. Note that the green falls in the same position in the rainbow pattern.