Paul:
As a Mexican, I can say that there is not much problem about spanish differences between countries, maybe a few smiles or laughs for some words that the locals will not catch, but it happens even from state to state in our country, not to mention between countires.
Here are some words used in different Mexican locations for meaning "kid or guy": Chavo, Morro, Compa, Amigo, Cuate, Chiquillo, Chaval, Chamaco, Niño, Bato, etc.
If you learn any basic spanish, you are on the road, then take a notebook so you can track record of the new words you learn from place to place, you will have fun.
In conclusion I would say that you will comunicate efficiently once you learn any kind of spanish.
Good Luck in your adventure
Humberto