Chamber size and other questions?

[Grover]

I've been reading, watching, trying to learn all I can but can someone help with dimensions?  I've seen different heights and diameters of separators.  What dictates the dimensions other than your collection container limiting the diameter?  Is there a height/diameter ratio?

Can a full 360 slot work instead of the normal 240 degree opening?

Another thing I'm puzzled about.  I see the air inlet and how the chips and dust fall through the baffle slot.  Where does the air that is being sucked out of the top come from?  Does it just spin around between the top and the baffle and then go to the center and then up and out? 

Sorry if these are silly questions.

[Enigmadan]

I think the diameter is generally dictated by the bin, but the height can be anything from the Inlet diameter up. Taller is reportedly more efficient.
The 240 degree slot is to reduce scrubbing of the chip bin (especially as it gets near full) by the air stream; otherwise chips could be churned up and ultimately end up in the dust collector.
The air leaving the separator through the top is the air that entered the separator from the Inlet, minus the chips. As it spins around inside the separator, it slows, the chips fall out of the airstream and through the slot into the bin, and the air, pushed into the center by faster incoming air, exits through the outlet.
The only silly question is the one that goes unasked.