You're right, I think 4' was too high (I was just estimating it in my mind). After thinking about it more, I think it's closer to 3 1/2 feet above. Anyways, I know I needed a bypass because the unit would click every so often, which was a sign of too much flow. Paul at OM said it wouldn't hurt the unit, but recommended to adjust the bypass ball valve until the clicking stopped.
And I wanted a lot of flow, so no, I don't think it's too much for my tank. Besides the flow I get from the Pan World, I also have a Mag 7 as a return pump, which adds even more flow.
Regarding flow charts, the Pan World is equivalent to the Blue Line Pumps, and here's one source I found for their flow rates:
http://www.mops.ca/cgi-bin/SoftCart.exe/skus/wp/WPBL-NH-150-PS-T.asp?E+scstore