looking for insight into life in Heredia

As for a phone you will want to have an UNLOCKED phone when you move here, one that will allow you to put a Costa Rican chip in it once you get here then put your U.S. chip back in if and when you  go back there. Then when you get to Costa Rica buy a cheap chip (like 1mil or 1500 colones) just to check the service in the area where you'll be staying. You will have a choice of Kolbi, Claro or Movistar and it all depends on where you live. A pre-pago (pre-paid) phone plan allows you to just recharge it at will and even though i live here full time I don't get a monthly plan, I just load about 5mil colones per month on it and that is enough for me.

I don't use Data a whole lot on my phone, I mostly use wifi for all internet connections and there should be places with free wifi around Heredia and of course in your home with your internet service. Here in San Ramon we have free wifi at the Municipal building downtown, and some coffee shops, restaurants and so on, for example.

If you might buy a new phone buy it in the U.S., it should be substantially cheaper there. Just make sure it will work on the sytem here. if you do an internet search you can find that info. Or maybe someone here can help with that info. Not me, I don't remember.

And you might consider getting a phone that allows TWO chips, that way if you're in an area with no service on one chip, say, Kolbi, then your other chip, say Movistar, may work. It's not necessary but is a nice luxury.

Before you rent a place check the internet availability and price at that very house and ask neighbors or other unbiased people if the service is reliable. ICE or Kolbi might be very reliable in one area for example and a couple miles away not reliable at all. That's just how it is here.

Again I'm not familiar with Heredia but in general CR has a pretty good bus system; not the most comfortable of buses especially if you're tall but a good reliable system and fairly cheap.

Taxis are not super cheap but not super expensive. Find out what the "official" taxis in your area look like and use only those. At least until or unless you might get to know a "pirata" or pirate taxi driver . ( I use a pirata because I know him and he's cheaper and very reliable but when I go to San Jose I use only official taxis.)

Any specific questions , not specifically tied to Heredia, you may want to start a separate thread.

Before you make this move, be sure that your potential employer is really providing you with a work visa as most language schools do not follow through on their promise. Getting a work visa is very difficult, especially to teach ESL. It can  take many months to get one

Please read this additional info.