Sell used iphone of other country

Hi All,

I have an iPhone which is 2 year old but this is from other country not bought in Europe. Now planning to sell of this phone. So my questions are,

1. Can we sell in Switzerland here other country phone here ?

2. I am not basically European hence want to sell without any risk can I do this or better suggested to sell in the country where I had bought?

3. Are there any good trustable sites other than comparis, ebay because there if someone asks in German I cant answer. Even if I get little less price I am fine with it.

4. Does any apple store buy used phone if so then I think that would be best option even if I get little less I am fine

Please suggest

https://www.apple.com/chde/trade-in/