1. Do they require any form of identification to use? Like a passport or ID card
Certainly you will be required to undergo a certain process before a transaction is been made, but I don't think it has anything to do with passport or neither ID card, knowing fully well that Bitcoin is an anonymous decentralized digital currency. As for those who wish to sell their coins, they will be given a certain Bitcoin address where they will have to transfer to their funds to from their wallets, and charges will be made with respect to the current price of Bitcoin and then it's equivalent value in dollars or whatever currency you wish to withdraw will then be dispense via the Bitcoin A.T.M. So that's how it works, and likewise vice versa for those who wishes to buy Bitcoin too. But just that the charges via using a Bitcoin A.T.M machine is always high.
2. When you want to buy or sell with it, does it have P2P trading? Or does the ATM and bitcoin belong to a company, and you're simply buying from or selling to them?
Yes, each Bitcoin A.T.M machines belongs to a certain company which makes sure it works smoothly. And all you have to do is trade with them directly just like in the case of p2p