I have a 36" Tri metal KM, it has excellent draw, so that shouldn't be a problem. And as everyone else has said, the thing at the bottom of the downstem doesn't really affect anything.
As for the vase grommet, everyone seems to complain about these, I like to view it as air tight perfection
I just get some water on the grommet and the lip of the vase, and then use a gentle twisting motion and she slides right in there. It's serisouly amazing what a little water will do. For removing it, I just hold the vase between my feet and use a gyrating kind of motion the the stem.
I've had my KM for a year, and haven't had anything but good times with it . . . you've made a good buy. The only thing I've ever had to replace was the ball bearing and that's it, just make sure you take a few mins to clean and dry and it should last you a long time. Most KMs come with brushes so it really isn't that hard at all . . .