They probably cracked the housing installing the new filter.

He is alerting you to forthcoming issues. The front rotors are wearing, which is normal and ok as long as they havent worn past minimum thickness. The rears are corroded which may not be ok come MOT time. He hasnt added any windscreen wash fluid because the reservoir is full. He hasnt fitted spark plugs because the car hasnt done enough miles to yet need them. They will need fitted at 100k miles.