First it is very hot in Jaco. Thought I was prepared for the heat index but wow is it hot. Not too bad if you are somewhere with an ocean breeze. But most of the main street is blocked from the ocean breeze. Take cool clothing! Saw lots of guys with no shirts but some places have signs "no shirt, no service". I always wore a shirt but wish I had taken some fish net shirts or sleeveless shirts, etc. Beer/drinks get warm very fast. A foam can holder won't help much.
As mentioned before most everything in Jaco is located on one long street. Jaco is a tourist town but a small town. I enjoyed being able to walk the whole town which has many nice restaurants, surf shops and tourist shops. A nice change from some of the large tourist towns in Mexico.
When I first arrived I tried to use my VISA debit/check card in ATMs at two banks with no luck. I finally asked a cab driver if he could drive me to a place that would take my card. He said just walk back 200 yards to the MasXMenos supermarket. There is a blue ATM in the front of the store that will give out up to 50,000 colones. This is also likely the best place to pick up some groceries. It is located closer to the south end of town.
Had a great time after I learned to live with the heat. Will try and answer questions if I can help.