Reamers, in general, want to be fed about twice the feed rate of a drill, at less than half the RPM. Don't ever turn a reamer backwards. I extract my reamer while the barrel is still rotating. I just pull off the feed and come straight out, or I ease up on the pressure and wait until the barrel stops turning as Mike suggests. My choice is dictated by how the reamer "feels" in the cut. Some reamers and some steels cut wonderfully and I don't worry about the reamer being hard to remove from the bore. Others... well, that's when I get the reamer out of engagement while the barrel is still rotating.
I do my chambering around 90RPM (or thereabouts) and when I clean out the chamber, I blow the chips from the muzzle towards the working area. I want the chips out of the "new" portion of the barrel, so I don't hang up the pilot on the reamer. Then I want the chips out of the area being reamed. I use brake cleaner or something similar to flush the chips towards the tailstock, followed by air.
OK, then as for lube: I like to use a lighter lube, with the idea that heavy sulphur cutting oil seems to retard chip removal from getting out the flutes of the reamer.
Before starting a chamber, I always examine the reamer closely, while wearing a opti-visor or a set of reading 2+ glasses. I'm looking for nicks, dull edges, problems with the pilot, etc. To start chambering, I'll use a twist drill about 0.070" under the diameter of the front shoulder, and then a boring bar set on the case taper to hog out most of the chamber area up to the shoulder - say within .040" diameter. On larger calibers (eg, .35 or larger) with .473 case heads, you might not need to do this, but I find it helps with smaller calibers - eg, 7mm or less with a .473 case head.
To clean off the reamer, I dunk it in naptha. Sometimes I use naptha to thin out cutting oil for lube, if I don't have light cutting oil available.