Good one, Piotr, and some very important questions raised. As others have referred to the Howey test as one of the few measures we have today, I guess it provides some guidance. Sure, US is not be all end all but it's a big and important market for crypto. Unless you want to shut your US investors/buyers from your offering, you need to take SEC into account. This is even more true considering that many other jurisdictions are in a wait-and-see mode.

A simplified version of the Howey test is: if you're going to be use your token to sell stuff, ie an means of exchange for products/services, then it's a utility.
If you promise token holders to make money off of your offering (i.e. any reference to token value appreciation), then it's more likely than not that some regulators will consider it a security.

Even though it's an oversimplified version of things.

And no, generally you don't owe taxes unless you sell your tokens to fiat.

Finally, the industry is still in its infancy and things will get clearer as it matures.

Note: Not a tax or legal advice, obviously.

Keep it up and good luck. :)