Question on chamber height and vertical placement of inlet pipe

[STDevil]

I love this site!  Funny story:  I recently built a dust separator.  It has a 90 degree elbow below the lid for the inlet, and a vertical fitting which connects to the vacuum cleaner.  As you already know, I was getting little eddies in the can (15 gallon drum) which caused some of the fines to be sucked out and into the vacuum cleaner.  I was just about to start experimenting with a baffle with a radial slot in it when I stumbled across this site and saw that someone had already mastered the issue – and the slot design made perfect sense once I saw it. 

Anyway, I have two easy questions which I can't seem to find the answer to:  Does the chamber height and vertical placement of the inlet have any effect on the performance of the separator?  In case it helps, here's where I am right now...

1)   I am using a 15 gallon steel drum.  It is 14" in diameter.
2)   I am using 2.5" diameter ports for the inlet and outlet.
3)   The outlet is installed in the center of the lid for the drum, and extends 1.25" below the top of the drum lid.
4)   The inlet will enter the side of the drum at a tangent.  I found this great site to develop the template I needed to cut the hole in the drum.
5)   I am not sure if the height of the chamber will make a difference.  I would prefer for it to be as short as possible.  Any thoughts on how many inlet diameters high it should be?
6)   I am not sure if the vertical placement of the inlet pipe (top of chamber, bottom of chamber, somewhere in between) matters.  I have looked at a lot of plans on the Interweb, and have seen all sorts of configurations.

Any help with #5 and #6 would be appreciated.

Thanks...