Well, if you're just starting out, here is a suggestion for some starting points.
There are probably as many ideas as people doing recording ;-)
> How far away should it be from the vocalist/rapper.
Between 6" and 15", depending on the sound you'd like.
The closer you go, the more bass you get.
> Should it be pointed down, up, tilted?
Point it, as a starting point, to the mouth of the performer.
If you hang it slightly above the person pointing downwards (to the mouth), if sometimes helps people to raise their head, and get in a better singing position, instead of lowering their head.
If the performer is using a stand to hold papers/text/scores, then you have to take that into account in the setup.
By angling it and experimenting with the direction, you can shape the sound a bit (less treble, more chest sound, etc).
> How far should the filter be away from the mic?
Anywhere between the mic and the mouth.
The pop filter can be good to control the position of the singer; place it close to where the singer should be. It will then prevent him/her from getting closer to the mic, and may help to keep him/her in a "steady" position.
> Should it be hung upside down or what,
Doesn't really matter much. Some would prefer upside down, so the heat from the tube does not heat the diaphragm.
-- Per.
