Do you have to have a valid driver's license to board a airplane

Yes and next year your license will need to be a Star ID. See your local state for details.... international travel requires a passport

Only an identification so they know who you are

You have to have a valid ID. That could be a state or you can have your passport. But it has to be a valid ID.

Yes most definitely and please get there 3-4 hours early if you're traveling Thursday-Monday unless you have clear or TSA pre check

Or a valid ID

Yes TSA requires it