Hi, I live 4 months a year in Panama. I have been through San Jose a few times the last few months. Staying for a couple days there. Last week I was there. My thoughts are...
Costa Rica is expensive.
Not, crazy expensive, but.. Raw materials, food, cars etc.., are more than the states. Also you have to hunt for cheap restraunts, as it isn't a given.
You can get by without a car. There are cheap busses and taxis are everywhere.
Immigration shouldn't be an issue... Since you are not working there, you will be a tourist. No fee for a visa.
There is a $29 exit tax. This is paid at the airport. I would investigate if non revenue passengers have to pay. Since you won't be flight crew...
The airport is a good 30 minutes from downtown, with minimal traffic. Longer during mid day.
The climate is very nice. I really like it. Almost perfect really, a bit much on the summer rain... But temp wise, no AC, no heat.
If you arrive with a bunch of other flights, expect immagration/customs to take a long time. 1pm on Monday, the line was 1:30 hours long. I timed it.
There is a bus stop right out front. Less than a 5 minute walk. It takes you to Alajuela, or San Jose. They run all night, but can be hard to get a bus in the early morning hours. They bypass the airport. It costs a $1.
Southwest is now flying from HOU to SJO. Might be nice if you are more convient to HOU vs IAH. Otherwise lots of flights from IAH to SJO. Also direct flights from a number of other hubs, ATL, DEN, LAX, Newark, FLL, MIA etc. Not sure how your schedule is, but might make sense depending on where you end the day.
If you find a nice apartment, convient to the Bus line, it could be a fun venture. With the right mentality, you can make it work.
I, like others here... Would recommend trying it for a month or two or three. You won't know if it suits you until you try.