VEVOR Pressure Washer Pump, 1" Shaft Horizontal Triplex Plunger, 4000 PSI, 4.0GPM, Replacement Power Washer Pumps Kit with Hardware, Compatible with Simpson MorFlex 40224, 40225, 40226, Santoprene

If you have a 1" shaft it'll fit. However you're better off buying a canpump

Yes

It looks like it would go on the bottom nut. This pump looks identical. “ Visit the ECCPP Store 3.5 AAAAA 17 ECCPP Horizontal Pressure Washer Pump for 1 Diameter Shaft 3300-4000 PSI 4 PM Replacement Power Washer Pump fit RSV4G40 EZ4040G EZ4040 Triplex Plunger Pump”

As for Pressure Washer Pump, there is no temperature control valve, but there is oil in the pump.