question MARK
There isn't a difference because they're the same thing.
You might properly call it a "tittle", but maybe not in polite company. Just call it a dot and everybody will understand.
We call him Mark because his name is Mark.
inside of quotation marks. It depends on what is being quoted and where the quote ends up in the sentence. It is safe to put the exclamation point where it most appropriately belongs: How could...