No 1. Mark 4 Ball which was not used in practice, was ordered to be returned to RL for disposal. I suspect this may have been one of those, reconfigured as a Mk. 2 Dummy. The fired primer would only indicate reuse of the case.
No. 2 this does not identify with any .303 military cartridge known to me. If the bullet is original, it would have to be used in a specially chambered rifle to avoid the bullet jamming on the lands.
No. 3. Appears to be as RichT says, a Gaudet drill round, possibly from a display board going by the in line holes in the case.
No. 4. Appears to be a dummy made in the field, viz an armoury. A Mk 3 from the factory should have a wooden distance piece visible in the holes.
No. 5 Could be anything. Absence of neck crimps would make it unlikely this is “real” dummy cartridge, by that I mean a military type.
Edit: On reflection the neck crimp on No. 2 is higher than usual and would possibly be consistent with the bullet cannelure on a Mark 2 or Mk 6 Ball. just a thought.