Usually there is also a nipple (looks like a vacuum port) on the top of the carb going into it above the throttle blades. Normally have a clear fuel line attached from the mechanical fuel pump to the port on the carb. If the diaphragm in the mechanical fuel pump goes bad the leaking fuel will get pulled into the carb. If you observe fuel in the line it lets you know the pump is leaking.

I'm not sure about CFM ratings being different from automotive, but they should be jetted richer than an automotive carb. Extra fuel will help a marine engine keep the EGT's down under the higher load conditions.

That's all I can think of at the moment.