You can add a Contract to an Event Type that has a Custom Form associated to it. When you view the Contract from the Event, the custom fields that have been filled out on the event will also appear. This will allow you the option for the customer to view the Contract and sign off on it if you choose.
You can even add an "internal" field (question) to one of your forms for just your staff to fill out that will not appear on the Booking Contract.
Here is an example of where we attached a Rental/Party Contract to our Party Event Type.