- if he has already instructed the transfer of bitcoin to me, even if it has to go through verifications, is this transaction "unconfirmed" ?
Yes it should show up on the blockchain as unconfirmed.
- using my bitcoin address (I do not have his) I should be able to see that pending transaction ?
Yes. But the comment "I do not have this" worries me. Why do you not have it? You most definitely should have it, after all you must have sent the address to the person who was suppose to transfer Bitcoins to the address.
Simplest way for us to help you: Post the Bitcoin address here and we can help you see what is happening.
- if that is the case, then we should be able to cancel the deal and he could revert back the funds I've sent him (minus the fees required for that transfer).
Well if he has already sent the Bitcoins to your address then it cannot be reversed. I assume that is what you meant by "if he has already instructed the transfer of bitcoin to me", that is not reversible.