Suppose I have a 1 out of 2 multi sig setup, which seed A in location A, seed B in location B and the public keys stored in location C.
question 1: If seed A is leaked, is it true the attacker still can't access the funds because he doesn't know the public key related to seed B?
As far as I know: yes. But, if the address has been used to send a transaction in the past, the public keys can be found on the blockchain already.
question 2: Would this setup be safer compared to having one seed into two places?
It depends on your threat model: safer from an attacker means an increased risk of losing access by yourself.
question 3: Can the attacker extract info if the seed is part of a multi sig setup?
See 1.
question 4: With the 1 out of 2 multi sig setup, can I put some small funds on addresses related to the seed in single sig setup, so the attacker would think he got bait, but in fact he only gained access to the small funds and not the full fund?
Yes. But isn't that what passphrases are for?