Registration: Drones weighing less than 250g are usually exempt from registration, but if the drone has a camera or other sensor that can record personal data, registration as an operator is required.
CE Marking: Drones under 250g should bear...
I flew in Switzerland last summer. You need the EASA registration on the drone at a min. The app you want is Skyguide, a guide to Swiss airspace. I drove in from Italy, so no customs concerns. Have fun.