A couple of years ago, I took Flybus to the Hilton Nordica. It indeed dropped me off right in front of the hotel door. I think I went to some main terminal and then got on a smaller bus and it dropped me off. Same with the return. Picked me up right from the portico. There was some confusion about the time of pickup though. Turned out I was looking at the time the bus to KEF left the central depot so was not out in front in time. The smaller bus had to come back and pick me up.

I did walk downtown from the Nordica. It was a nice walk. The Hilton will give you bus passes to get downtown and there is a bus stop right across the street from the hotel.

Flybus is definitely the way to get to the KEF airport, it is not very close.