Thanks for all the replies.
John: For adding mist I had thought it might be possible to inject a very small amount of fluid through an airbrush type nozzle into the coolant line, where it is mounted to the head of the mill. The fluid would have to be under pressure to do this, I had not got as far as thinking about how I'd achieve that. As for the pumps, I think I got lucky and hit an ideal flowrate at 70L/min. Pumps are available much smaller than that, and a lot bigger. If I had much more, the chips might be able to escape the enclosure and I didn't really want a roof on it. If you wanted a couple of jets, something like a 250L/min pump would work very well I'd bet. It's nice that they are continuously rated too.
Lee: Good point. Humidity is not a problem here in the UK. To be honest I am more likely to get the mill floated down the road in a freak flood. Already had some flooding round here this year.
Paul: Thanks
. I am hoping to get a belt drive on there soon. Can't be bothered making one so I was just going to buy the LMS kit. I've been lucky and only destroyed one gear in the 4 years I have had the machine. That was when I forgot to bolt my vise down and it smashed a 10mm HSS 4-flute cutter too!