You have the formal French language and slang. I guess, the most important is to know how to use "tu" and to use "vous". Tu : is used with people you know (relatives, French), it is also used between teens (people of the same age use "tu" to talk), adults use "tu" when they talk to children. Vous : is used to show respect (so you use "vous" at work when you talk to your boss for example), you use "vous" with strangest, "vous" when you talk to many people at the same time. Some people might find it rude if you say "tu" to them while you don't know them. That's better to start with "vous" and then wait for them to say "you can say "tu" to me".

Tu and Vous mean you in French but Tu is singular, used for friends. while Vous is plural and used for strangers/seniors.

Of course it has. For example, zut means devil, buolot means job, dodo means home,sleep...