The only problem you might run into is that, at least with Irish Gaelic, like any other language, people from different parts of the country sound different when they say the same things. Watch out for that. Learning the language would make learning the songs easier, but not necessarily make it possible to decipher what someone is singing on a recording without having the words in front of you, depending on where they're from.
I don't speak it (yet), but having "learned" songs from several different albums/artists and attempted to learn how to pronounce things based on that, it doesn't work very well unless you always listen to the same person.
-RB3