if you got any seat in any of the medical college in the first round then you have to go to college for manual registration.if you haven't got any in 1st round then there is no need to go.For details please follow the admission and counselling procedure given by odisha govt.

No , you cannot because some documents verification happen in first counselling which is necessary.If you have missed the document verification that is the first counselling stage you can not apply to the second counselling stage which includes the confirmation of the seat . 

Hope it helps .