Q147: Can I add a rental agreement (contract) with terms and conditions of a rental?

Yes, you can do this in 'reservation form layout' (more info here). You'll need to add an item of type 'Agreement'. Set 'name' to e.g. 'License agreement' and comments to the contents of the agreement. If you want the agreement to open in a new window (e.g. in case it's very long), instead of typing its contents, enter the URL where the agreement is located, starting with http://

Your visitors will then be required to agree to the conditions, or their reservation will not be entered into the system. You will also clearly see that the conditions were accepted by given customer when you go to the reservation details page for given reservation.