Not entirely sure this is the right forum for this, but I have no idea where else to do it so here goes.

Anyone know the legality of using lyrics from real songs in the a novel? if I wanted to use an old song, lets say la vie en rose, would that be legal?

For legality issues, you need to consult a real lawyer that knows the laws within your state/country. Or you can look it up yourself, but if you go to someplace big like reddit you'll be able to find a lawyer who will help you for free. Still, I'll give you some info from what I know. Just know that I'm not a lawyer, and I could be steering you on the wrong path. There are many intricacies in law that someone outside the field doesn't know about.

As far as I know, copyrighted material requires permission from the owner of the material in order to use it, and you are not able to gain monetary value form its use, or anything related to its use unless you gain express permission from the owner of the copyrighted material. A material loses copyright after a certain amount of decades and becomes 'public', in which case anyone can use that material without any repercussions. That's why material such as shakespeare is used so freely. Walt Disney changed that legislation so that it is longer now, unfortunately, so you'll have to find out just how many years before a copyrighted material can be made public.

Otherwise, you can make use of the 'parody' law which falls under fair use. That is, as long as you alter a piece of work enough that it is considered a parody, or in a way your own work, then you are able to use it without permission from the owner, and are able to gain monetary value from its use, or anything related to its use. However, be aware that it is possible to take you to court over your parody if it is deemed too close to the original, at which point you might be looking at being sued and losing the rights to your published work. That is a worst-case scenario however, and very unlikely to happen.