Electric fuel pumps, (Chugger pumps) do not have a cut off.... But they have a low enough fuel pressure that the needle and seat should hold back the fuel.
Yes! That means that if you have a faulty carb (bad bowl gasket, bad float, bad needle, etc) you may very well empty your fuel tank into your engine compartment.
If functioning properly, it won't have a problem. The anti backfire solenoid was removed from later models, it must have been found to be unneeded. I have cut mine and have no problems. I do not even turn off the fuel valve under the tank by the filter.
And you're right, you have to have a pump... It won't gravity feed (enough) to run the engine.
I have a pertronix electronic module in an old points distributor. Mine will NOT start cold without a LOT of fusing. Once warm, it generally starts like a dream. I think my timing is too far off to start due to the bad distributor shaft.