Stay healthy:
Costa Rica has one of the highest levels of social care in the world. Its doctors are known worldwide as some of the best. Many people from U.S, Canada and Europe go there to be treated, not only because the quality of the service but for the cost. First class Hospitals can be found in the capital. There is a public/private hospital system. There is excellent care in each. The public system has much longer waits, while the private system has shorter waits. If you are unfortunate enough to have a very sick child requiring hospitalization, the child will be transferred to the only children's hospital in CR, located in the capital. This children's hospital is public.
There have been outbreaks of dengue fever in some areas of the country and an outbreak of malaria was reported in November 2006 from the province of Limon but just a few cases. Protection against mosquito bites is very important, wearing lightweight long pants, long sleeved shirts and using insect repellents with high concentrations of DEET is recommended by the CDC. If you are going to be in very rural areas known to be malaria-infested areas, you might want to consider an anti-malarial med. However, most travelers to Costa Rica do just fine with updated childhood immunizations and taking preventative measures against mosquito bites (rather than take anti-malarial medication).
Tap water in urban areas of the country is almost always safe to drink. However, being cautious may be in order in rural areas with questionable water sources.

Contact:
The international calling code/country code for Costa Rica is 506.
A postage stamp to Europe is 125 Colones (around 21 US cents).
The primary means of outside contact are through email and public pay telephones.
Internet cafes are fairly easy to find in tourist areas, with prices all over the place. Some of these offer long distance calls over the internet.
Public phones are accessed with calling cards (tarjetas telefonicas) which can be purchased at most shops, even in outlying areas.
There are four different types of pay-phones:
Coin phones. Note that these only accept the older silver-colored coins.
Chip phones. These phones allow you to insert a chip-type calling card into them and make your calls.
Colibri phones. These phones have a small swipe bar for a scratch off type calling card referred to as a Colibri calling card which are available from 500 colones and up. The swipes often don't work ou always have to enter the calling card access code on the keypad. Despite this, the Colibri calling card is the recommended one to buy as you can use it any of the types of phones whereas with a chip card you must search for a chip phone.
Multipago (multi-pay) phones. These phones accept coins, chip cards and colibri cards. Most public phones around the country have been changed for this type of phones. They also allow you to send SMS messages and emails as well.
Both types of calling cards are typically available in pharmacies and other locations where you see the sticker on the door.
Domestic calls are quite cheap and the price is the same wherever you call. Calls to cellular phones are charged significantly more though.
International calls are fairly expensive. The cheapest way to make them is over the internet using a service such as Skype at an Internet café. But making short calls using the domestic calling cards (you can make international calls using these but the denominations of the calling cards are quite small so your call will be short!) or the international calling cards available within Costa Rica (all from the government phone monopoly ICE) is the next best deal. Certainly better than credit card calls or using a US calling card generally.
Mobile phone service in Costa Rica is provided by Grupo I.C.E. using GSM technology at 1800 MHz and 3G operating at 850MHz (this is not a standard 3G frequency in many countries - if you want to use 3G make sure your phone has that capability). Roaming is possible with a GSM handset but can be expensive. Several US companies including Intouch Smartcards offer discount global roaming SIMs for Costa Rica that can provide service in Costa Rica at reasonable rates. Note that the GSM phone systems in the United States and Canada use different frequencies and that travelers from there will need a "world" handset. You should check with your provider beforehand. Prepaid Sim cards are now available in Costa Rica, at the ICE kiosk in the arrivals area at the airport and from ICE offices in Costa Rica. Prepaid SIM cards expire in 30 days.
All reports indicate that most of the country has very good GSM coverage (including most of the capital), and that TDMA coverage is much better. Non-residents may rent cell phone service, and of course anyone can buy a cell phone, but you must be a documented resident of the country to own your own cell phone number, and even then you will only get one if there are numbers available, which is no longer a problem now a days. Prior to establishing residence a corporation can be formed and the corporation can receive a number. The fee for establishing a corporation should be no more than 300 dollars. Grupo ICE is a government-sanctioned monopoly, and they prefer not to overextend their resources.