Sears Gamefisher 5HP engine questions...

I have a 1989 5HP Sears Gamefisher outboard engine, black in color.
Model number = 225.587501
Serial number = 5069

I "think" this is the same as the Mercury "Force" 5HP made in 1989.

Questions:
1. Is the engine water cooled, or air cooled?
That is, does the impeller cool the engine, or just the shaft?
2. Will the 5HP Mercury Force parts interchange?
3. Where can I go to get low priced parts, like the impeller, etc.?
Sears is outrageously high in price.

Please email me at:
if you have time.

THANKS,
Gene