Q: Does it violate the 3rd Law to bargain with a spirit to read someone's mind for you? Say you get a memory spirit to look in someone's head and bring info to you?
Possibly, depending on how you got in contact with that spirit. See YS285, the end of the section on diabolism, where it states that summoning a creature to act in your stead is just as much a violation as direct magic. On the other hand, if that spirit is just an NPC who hangs around in a skull in your lab, needing no magic to call up - I'd say that's not lawbreaker material.
(re-posted the following question, since it didn't get any answer previously, and this is definitely the right thread for it to be asked in.)
And, for a slightly different lawbreaker question: Transforming someone else, body or mind, is against the Laws of Magic. Transforming yourself is not. But what about giving someone else the ability to transform themselves? Is giving someone a hexenwulf belt you made a violation of the laws of magic? What about a potion of turn into a wolf 'till the next dawn (that, presumably, doesn't have the demonic possession drawback of a hexenwulf belt)?