I'm not in Finland or an expert on their taxation rules - my statement was based on a quick read of some of the information I found, but I would assume that if you chose to get paid in bitcoin than yes, you would have to determine the value of the bitcoin when you received it and pay taxes on it. When you cashed it out you would either have to pay taxes on the gains or eat the losses.

Income is always taxed, so yes, you would get taxed.

Wealth taxes ignore property rights. When something is yours, it should stay yours unless you agree to part with it.