@Cheryl-Ann0
You can manually adjust nightly rates as you want but ABB does not offer the option of having different "rules/charges/policies" applied for specific periods.
If you set $50 for additional guest after the first guest, security deposit of $200 this will apply to all reservations made as long as these are your settings. So for instance, if had a $200 desposit today and were to change to a $300 deposit tomorrow then reservations made today will have a $200 deposit and reservations made tomorrow will have a $300 deposit regardless of when the actual guest stay will take place.
Also, from what I know the system does not support discounts based on no. of guests - only weekly/monthly discounts can be applied. I think there is an option for early bird/last minute discounts but I am not sure.
You should do a search in ABB Help and also check each of the availability and pricing settings pages (under Calendar) one by one to get a better idea of how things are set up.
https://www.airbnb.com/help/topic/1042/pricing---availability
Hope this helps~