Once you have found the topic that you like then go from there. As for the language, there is no specific languages that you should know. You want to be able to communicate with the people you are working with. Egypt for instance, you might want to know french, and arabic. It all depends on where you want to work.
Archaeologists can do various things.
What you need to do is find out what you like and go from there. If you really are into archaeology it won't matter what you do as long as you can be out there working in the field and can enjoy what you are doing. From there just research them to find out which one you are most interested in studying. You don't have to get specific until you are well on your way through college. Yet it would be nice to have some sort of idea as to what you want to study.