Friesians are black and white and produce lots of milk
Herefords are brown, much furrier and are bred for meat
There is no difference, they are just different ways to spell the same type of cow, just like theatre and theater are the same word.
The genes.
A Friesian bull has the very same colouration as a Friesian cow: black and white.
No. A Hereford cow will only give birth to a Hereford-Limousin cross calf if bred to a Limousin bull. Only a Limousin cow can give birth to a Limousin calf--IF she's bred to a Limousin bull. Just like a Hereford cow can only give birth to a Hereford calf if bred to a Hereford bull. Otherwise, she too (referring to the Limousin cow) can give birth to Hereford-Limousin-cross calf if bred to a Hereford bull.
Black and white.
Both will work just fine. Neither cross will have the desired heterosis like Hereford on Angus or Hereford on Charolais will.
There is no difference.
The Holstein-Friesian, of course!
Holstein Friesian cattle
Yes. They are more commonly referred to as Holsteins.
An Angus or Galloway cow would be, yes, but not a Jersey, Simmental or Hereford cow.
Yes there is, as a matter of fact. The most commonly known Friesian is the Holstien-Friesian diary cow. There are several different types: British, Dutch, German, Danish, Italian, Argentinian, Polish and Swedish. There also exists the American Beef Friesian. The second Friesian is the Friesian horse, and there are also Friesian sheep.
Hereford is a pure breed, and the origin of the colour pattern of the Hereford breed is pretty much unknown. So you can't find two breeds to cross to find Hereford, unless you can find a Hereford cow and a Hereford bull and "find" a Hereford calf!