How much money to bring, and how much to bring for 2 weeks?

I will be staying in costa rica for 2 weeks in december starting from the 21st. I’ll be staying in sarapiqui, escazu, san jose. ill be getting picked up from and taken to the airport when its time to depart. i wont use a taxi. i dont plan to spend a whole lot of money. a few souvenirs here and there for me and maybe 3 family members. whats the minimum amount i can take that will last and stretch? whats the most amount that could come in handy? also, can i withdraw from my debit card when i bring that along and are cashier checks advised to use at a bank there? i hear its advised to bring us money in $20 dollar bills or smaller. its my first time traveling alone, and id like to have enough money to at least leave something for the 4 families ill stay with. how much is the departure fee at the san jose airport?