Hi,
You first have to setup your listing properly, including celaning fee, security deposit and prices for extra guests.
If a guest is booking, you can not change the offer afterwards with extra amenities, which normally should be in the listing.
After confirmed booking you can exchange phone and/or email if desired, it will not be blocked.
Also you can change the reservation, for example if there was a mistake from guest (like booked for 1 person, but must be 2 or amount of nights must be corrected etc...) . But (offcourse) your guest has to confirm this change.
Hope this helps,
Emiel