There are 3 differences between the regular version and contract version.
Press the Create Escrow Button. If the Escrow Factory contract has DAI approval for the required amount a new Escrow will be created. If the DAI approval is less than the required amount, there will be 2 transactions. One for DAI approval and the second to create the new Escrow.
Yes, because that is how ERC20 Tokens work. The Payer address will need to give DAI approval to the Escrow factory contract for a certain amount. The DAI approval amount can be set
before hand or at the time of creating a new Escrow in which case each Escrow will require 2 seperate transactions.
If the Escrow Payer plans to use StableEscrow often they can give DAI approval for an amount equivalent to a few Escrows, rather than set an infinite approval like most other DAI enabled apps request. Giving infinite DAI approval to a contract address could turn out to be a security risk in the future.
All parties get paid when the contract settles.
ENS is the Ethereum Name Service. If the user has registered their Ethereum Address with an ENS name, then type the ENS name and press the ENS button. StableEscrow will query the ENS registry and if a record is found, it will automatically populate the user Ethereum address.