I honestly have no idea about the number size needle I use because once I buy them, I take them out of the packaging and stuff them into my pin cushion!!
I can tell you that I use a very short needle, but it has a fine point. I use the shortest needle I can find, I find I have more control with them for smaller stitches (my hand stitching is very very tiny). I think the one I use is about 1.5" long.