After having lived in CR for 4 years all I can give you please be careful. If you are renting a vehicle at the airport, remember to fully check your vehicle as otherwise when you return the vehicle you could be charges for items such as spare wheel missing or jack and wrench missing. Check your vehicle carefully, remember that you may think that by renting from a main well known brand in say the USA or the UK does not mean that you are safe, as in CR you are dealing with a completely separate entity.
CR is the land of opportunity, do not give any body the opportunity to steal from you. I am not saying that CR is unsafe it is very safe, just be careful and keep your eyes open and be careful.
Restaurants are as a general standard very good, water is good, hygiene is good, food does tend to be cooked in oil and fried food is common, tipping is expected 10% is fine.
Hotels are of a good standard and are owned by Ticos or Ex Pats.
Enjoy CR it really is a wonderful place, just be careful and keep your wits about you.