If i do nothing but sit all day except for going to kitchen and to store will i be off balance when i stand and stuff . and get dizzy?

No, not really: Going to the store is enough activity to prevent one's body from getting too out of shape and too used to being sedentary. That means one should be walking to and from the store, and when inside, one should cruise up and down the aisles, thus getting plenty of walking exercise.

Yes.: And you won't live as long as someone who is active.