Hi, does anyone know which interface is used on an Evo?

One to work with the multiscan software (or any other).

Also, what can you actually do with it on the free version?
Can you read fault codes and get a list of what has been happening on the can bus?

Its EOBD2 that on the punto's (16 pin trapezium shape port) and I'm sure most people use FES (FiatEcuScan). Very good software. As for finding out whats happening on the can bus, you'll need to make something up to connect to the CAN (Both High speed and Low speed or Dual Wire and Single wire).

Or buy the hardware on FiatECUScan that do all this automatically (but the price is a bit high for DIY on 1/2 cars...)