yes, you can play the game even if you don't own tokens. No, all of the items you can purchase with tokens are cosmetic only and will not give plays an unfair advantage in game.

SKARA is a free-to-play game such as League of Legends or World of Warcraft (around since 2004), so the plan is to keep updating it for unlimited time and also release new games in the SKARA Universe which will use the same currency, so it can last forever. What is called games as a service instead of a product.