@Rachael-And-Bob0
The security deposit can not be charged in the special offer, you must include it in your listing.
The only way to precalculate Host ans Guest totals is using the price-calculator (part of the calender)
But then the monthly price must already be set for the specific months (in the pricing section for specific months)
Otherwise you can estimate the Airbnb Guest Servicecosts by simulating a montly booking on your listing and check which percentage is used to calculate the Guest Service Fee and also check the amount of taxes (if any) applied.
In my country Airbn Guest Service fee for long term stays is 12,66% (includes 21% VAT) , but as you are in the US things can be totally different.