1. Magicians like Criss Angel? Or people like Aleister Crowley, Raymond Buckland, Doreen Valiente and so on? Or people like Merlin? Criss Angel is an illusionist, not real magic people on this site cast. Merlin is mythical, while there is some evidence to support a real Merlin, some of his tales are probably untrue.
2. Unsure, but no on both points.
3. A grimoire and B.o.S. are the same thing, they are books made by a practitioner to record their work. Never heard of someone calling it an almanac but it would be the same thing.
4. There are tons of different forms, healing, Faerie, green, black magic, elemental, voodoo, potion, blood, dragon, satanic and many more.
5. You talking about a secret council of witches? No there isn't one. on this site of course there's people who are mods or admin who watch over things, and also you've got a similar structure in many covenant but that's about it for councils.