If I am on 5 % Minoxidil, would Rogaine make me lose hair in parts I don't apply it?

Regain can cause a temporary shedding in the initial phase of application.  This lose is most likely because hairs shift into the growing phase from the resting phase.  The old resting hair is pushed out and soon replaced by an actively growing hair.  Application in one part of your scalp, should not cause you to lose hair in other parts of the scalp.  There could be some absorption of the minoxidil that could temporarily influence the immediate surrounding area in the initial phase.  Shedding suggests that you will respond positively to the minoxidil so don't "freak out" if you have an early, but temporary shedding.  many people panic when they start to shed on minoxidil, but this is temporary so remain calm.  There is a test you can have performed to determine if you are showing early signs of loss in other areas due to male pattern hair loss.  This test measures your hair mass and you can compare the hair mass in all parts of the scalp to see if there is evidence that you will later see a pattern of loss develop.  

No, minoxidil effects are largely localized - meaning that it acts  in the areas where it is applied but not in other areas. Of course, if you have male balding, you may develop hair loss in other areas as part of the natural progression on balding. However, this will be independent of one's minoxidil use and application to other areas.

No, putting Rogaine on one area will not cause other areas to lose their hair. Most commonly there is some shedding in the immediate area it is applied temporarily, before stimulating more growth in general.