boehme I read with interest your suggestions and the use of my diagram.
1] I placed the Filter as clode to the Pump Inlet as possible so that ANY ingress of Dust is trapped, any joint in the piping or failure of upstream filters could result in Dust getting into the Pump. The Filter is there for a purpose and you should not be too concerned about the amount of Dust it is exposed too.
My experiance is that in the 3 years this has been in use I have cleaned the Filter only once.
2] If you really want infinite control the Needle Valve is the solution but they are both expensive and, in my opinion, uneccessary.
I get adequate control if needed but generally it remains closed.
3] Positioning of the Gauge is irrelevent, a Vacuum is that a total negative pressure in the system you will get the same Reading whereever you have the Gauge on such a small volume.
Incidently my adaptor is not a rotary adaptor but a fixed adaptor.
4] Not sure about this shut down procedure, it is not mentioned in my instruction manual???
3 years of use, at least 200 woodturnings attached, and it is still performing well, you do not have to overcomplecate it.
Richard