You can "declare" the car after you arrive if you did not do it at the border. To get the Swiss numberplate you will need the customs declaration (which is really, really easy), proof of Swiss insurance and a road worthiness inspection.

Transferring your licence is completely independent. But when you inform the STVA that you are importing your car and they send you the paperwork for that, they will probably send you the licence application form. You might as well do it at the same time rather than leaving it to the last minute like I did.