Questions about minions for Demonology

[chiperinooo]

Hey, I’m new to WoW and I have some questions about the demonology spec. I’m playing Wrath of the Lich King.
1) how do I get soul shards? Do I only get them from the Drain Soul spell?
2) What is the max amount of minions you can have at a time?
3) I know that there are temporary minions such as imps (from hand of gul’dan) and Fel stalkers, are there any more?

[Overloard99]

1. From drain soul spell only, i'm not sure if there are others.
2. At the time > only 1
3. Voidwalker, felguard is one of the best for demonology.