WW2 and after:

1937 Pattern - WWII British Webbing Set - Military Surplus Collectors Forums

Look for the link "1937 Pattern - WWII British Webbing Set" and it will describe the set in detail. Ammunition was carried in the utility pouches, it could be kept in the bandoliers and the bandoliers neatly folded in to the pouches or it could be loaded in the pouches in the individual chargers.

As far as the bayonets for the No.4 being dated, no, they were not.

Out of curiosity, what are the "leg drop 3 pockets" that you mention?