Ok, I am about to start the Conjuration Ritual Spell from Phinis. I see that you get some thrall type spells at the end (can purchase). My question(s) - it says that you can summon the Flame, Ice, Storm atronach permanently for 999 days. Does this mean they follow you around nonstop? Suppose I don't want them to follow me for a while. What then? If I dismiss them, can I get them back again later?