I'm often making ghee for my cooking. However, I've never seen how it's done, I've only read how to do it, I'm having some doubts about its preparation.

1. Should heat butter slowly or fast? I saw both directions in recipes and I don't know which one is better. Or does either of them have some advantages?

2. When I know ghee is ready? When cooking it, it goes roughly through these phases:

   1. Foam is forming (and I'm collecting it and putting away).
   2. Foam gradually stops forming, but white pieces are floating in the liquid, I cannot see the bottom of the pot.
   3. The liquid becomes clear, solid whitish pieces are lying on the bottom. Small bubbles are still forming.
   4. As the pieces on the bottom turn dark, small bubbles eventually stop forming.

   I believe the proper time is somewhere just after 3., but I'm not sure about that. I don't want it to get burned, but at the time I want it to be really pure. Some sources claim that ghee is ready when the surface becomes completely still. But this doesn't happen until all the pieces on the bottom turn dark, and I feel at this time it's like a bit burned.

3. If I want to keep ghee for a long time (I've read that the older the better), what is important to be aware of in order it doesn't go bad?

_{I couldn't add tag ghee to the post, if someone has enough points, feel free to do it.}