Everytime or Every time both refer to each occurrence or instance of an event or action, but "every time" is the standard form in written and formal communication.
Drier is an adjective used to describe something with less moisture, while dryer is a noun referring to a machine or device used to remove moisture from items.
Used to is the correct form when discussing past habits or situations that have changed, while use to without the "d" is incorrect in standard English usage.
Theater (American English) and Theatre (British English) means performing art form that involves live presentations of stories and performances by actors.