[Ethereum] Transfer ERC20 Token feeless

I think it has to ultimately be human verification, unless it exactly matches an existing contract that's already been verified by humans. Even if all the functions that are supposed to be in the standard are there and do what they're supposed to, you can't be sure that somebody hasn't done something unexpected in a different part of the code.

It's probably not safe to rely on exchanges to add a given token to be auditing the contract code, although it would be certainly be good to have some kind of process for this.

Right, it is possible to implement calls to tokens from an escrow contract.

1) You can make an escrow that will support any kind of token (as long as they implement the expected abi).

2) Yes, all evm state changes made by a transaction where the gas runs out are reverted.