B.Cooper 8-12 tpi (fine pitch) at what speed would you use for a 40 mm hole saw?
As fast as my DeWalt goes ;-) 1200rpm or so I think.

Manual feed, definitely - I find that I don't need to push much at all, it pretty much pulls itself into the work. I was worried about snagging too, but best thing to do is have a go with some old tubes and see what happens.