@Abby9, you have Instant Book turned on, which is why people can book without prior notice. If possible, try to turn it off.
If there's no way to do that - AirBnB has selected many new hosts to be 'guinea pigs', and they're forced to use Instant Book - contact AirBnB and request that they deactivate the function.
I strongly urge you to request a Security Deposit, especially since your listing is geared to accommodate a number of people. The amount should be equal to cover the amount of possible damage you might envisage happening to your property.
The deposit will show up automatically on a guest's booking comfirmation. No money is taken from the guest's acount during the process, so there's nothing to 'refund'. The deposit is simply 'held' in the event a claim is made against it within 48 hours of a guest's departure.
I also strongly recommend that you make your House Rules much more specific. Draw up a serious list that shows clearly the boundaries that guests are required to respect. Without house rules being visible on the page, AirBnB will not back you in the event that there's a problem.
Here's a link to some essential reading for hosts.
Contains a link with several international phone numbers (‘How to contact AirBnB’).
https://community.airbnb.com/t5/General-Hosting/Community-Help-Guides/m-p/23100#U23100
Donna