Fighter ammunition

Hello all ol' warriors!
Usually, it seems, most WW II-fighter aircraft which carried cannon had got 120 rounds per gun (rpg) from 1941 on, i.e. as soon as belt-fed systems were manufactured and introduced. The French Armée de l'Air started with this in June 1940 actually and the Bloch 155, an improved 152, was the first type to get it ant it was used just a little on operations before the armistice. No doubt all other French-made fighters would have followed suit quickly but the defeat on the continent prevented this from happening (too bad). The big advantage was that the ammunition jumped from 60 (with the old drum) to 120 rpg. Also, it was much easier to find room for an ammo box than for the big drum containing 60 rounds. Like the French cannon itself (Hispano-Suiza HS 404, called "Hispano") the belt feeding system was passed on to the RAF.
The Germans introduced belt-fed cannon on the Me 109 F, about January (?)-April 1941, jumping from 60 rpg to 120 too IIRC. By the way, did they adopt the French system, which was ready for use when they invaded France in June 1940, or had they already designed a teutonic system anyway?
2ND QUESTION : I think I remember some authors mentioning 200 rpg. Is this true? Was it implemented on fighters? What about bombers including the B-29?
Thanks in advance.