You should be able to go down to the "minimum" mark without the risk of engine damage, although it is better to keep it near "full". You will have a greater safety margin that way. Checking ones fluids is a good thing to be a little compulsive about. Once a week should be the minimum. More often if your car consumes oil or fluids. Make sure it is level; even a slight tilt or incline can make a significant difference in the reading on the dipstick. Can't think of any particular reason to high rev an engine after changing the oil. The "vacumn in the oil filter" sounds like BS. I suppose revving it to a fast idle might bring the pressure up a little and help check for leaks, although if it has a leak it should show up at idle speed also.