@Milena87
1. Any surcharges are not well received. If you decide on surcharges, it must be mentioned in the house rules and also in other things to notice and preferably also in the description and the pre-booking message. Once there is a booking, you would need to inform again to make sure the guests understand and agree. All correspondance would need to be documented on the airbnb platform in case of disputes. Upon agreement, you would need to claim through the resolution center. Due to these issues, you cannot accept last minute reservations, so make sure your settings are set accordingly. You would also need a cancellation policy that allow guests to cancel free of charge in case they do not agree to the surcharge.
The easiest would be to increase your prices during the period in question.
2. You cannot - you simply lower your prices.
3. Smart pricing is not all that smart and does not work well with seasonal price variations. I suggest you set your own prices.