You mean a drip tip yes? They don't have filler in them. The point of them is to allow you to direct drip onto the atomizer bridge, without having to remove anything. The old way, before drip tips came about, usually involved using a blank mouthpiece or cart without any filler in when dripping. How many drops is not an easy question to answer. Two to
three would be the way I do it. Drip again when the flavour weakens, or if you get any burnt taste. It's kind of an art rather than a science

If you get excessive amounts of liquid running out the bottom of the atty, you might be dripping too much, in which case ease back on the amount. Some leakage is unavoidable.