Hi,

Yes, If you feel like you are satisfied with the seat then you can surely go to the reporting centre and put that to float or you can freeze too.

I would suggest you to float the seat so you will have other options too.

I wish you best of luck

Thank You

No, you  cant add in between the counselling process. For the addition you must try for the spot counselling in case you are not good with the colleges you have listed for couselling in your normal rounds as the sequence and the number of colleges remain the same till the end of counselling procedure and you only get the chance of refilling it in spot round.