Super great questions...

Swapping between crypto on the app is supposedly free of fees (but they say based on coinmarketcap rates). From Crypto to FIAT, I think that does not apply much to Crypterium yet, because they don't handle FIAT within the wallet. But there are fees for moving crypto in/out the wallet.

About taxation, is the usual. We have to do the homework and pay ourselves the taxes. About their side, I have no clue, but that shows even greater knowledge from your side. =) Will be sure to investigate if you know more stuff I need to know.

thanks for stopping by...