Sommaroy - how to get there

Hi! I’m arriving in Tromso at night (around 23h), and my hotel is in Sommaroy. I have no idea of how I can get there.

It looks like my only option is to take a taxi but do I have to get it scheduled beforehand or is it easy to get one at the airport?

And then when I have to go back to tromso, I saw the bus line and it doesn’t run very frequently, is there any other option other than taxi?

How much is it gonna cost each way approximately?

Thank you for your help!