Okay at first I thought it was called a vacuum bed, but if you search google and find the wiki link on that you will know why that is not what I want!

I know roughly how I need to build it having read a few build logs but I do have a few questions.

Firstly I am not sure if I want to use a vacuum cleaner to suck the piece down or a vacuum pump. I will be looking to mainly to hold down 1/4 sheets (1200mm x 600mm) of MDF and ply for routing. When I start cutting hole and parts out though, the vacuum will obviously be broken so I wonder how much flow rate I will need from my suction device. Typically I might be cutting out 8 parts from the 1/4 sheet each about 300mm x 300mm and I could use a 3mm mill to keep the gap around the parts minimal.

Looking at eBay the pumps tend to range from about 50l/min to 120l/min. Would this range be okay for my work or do I need something with far higher flow rate?

Just what sort of flow-rate do vacuum cleaners have anyway? I did a quick google and found one that claimed 42l/min so that seems to have no advantage anyway, unless it was a typo.

I understand the need for a vacuum chamber to give a good suction at the start of clamping while there is not a good seal at first. However what about dust and stuff getting sucked down? If I'm using a pump I presume I need a good filter too. How would this be done? Is it enough to place some open-cell foam over the reservoir inlet or might this just get sucked into the chamber anyway? Maybe fill the chamber itself with wire-wool?