How do you say, if there are more than two things? I don't think "either" can be used.-- Actually, sometimes it is. Can I say, "You can take A or B or C or D"?-- Yes or "You can take A, B, C, or D"?-- Yes, this is the more usual form.
If I say, "A, B, C, or D," do people misunderstand that it means "A+B+C or C"?-- No, they don't.