@jamal khan yes u need the same docs from your employer to renew and yes u need to renew ur work permit first. Visa u can do later in Jan 2019. Usually it takes 2, 3 days to renew but sometimes they do extend on a same day also.
Yes right behind immigration counters... Let IO know at immigration counter that u need re-entrt permit. He will do paper work accordingly and handover u ur passport and departure card and direct u to room behind him.