No, you can not 'freeze' your subscription. You will have to waste those two weeks I'm sorry to say.

Your second question, no, you don't have to keep paying your subscription. If you know you won't be able to play for a month or two (or twelve), just cancel your recurring payment plan and your account will become inactive. All your characters, gear, gil etc will be unavailable for log in but will be stored safe for when you do decide to pick up the subscription again.