Do you plan to add Tether to your exchange?
As they stated earlier there will be some Fiat pairing in start and tokens will be listed in some interval of time.
That is cool, but tether is no FIAT

Yeah, to be honest I would prefer TrueUSD over tether.
Why do you prefer TrueUSD? Is it better then tether or you just like it more?
Can someone explain those two and the difference to us n00bs?
there is not much difference both are equal to approx 1 USD.
Most or all of these decentralized currencies are fully centralized, which means that from one second to another the coin could crash or get hacked or something and there is no more dollar value.
Then why would they proclaim they are decentralized? What's the purpose of that?
They are not decentralized as long as they work as a (fractional) reserve system. If you have a reserve, you usually have to have a centralized governance body. There are experiments for decentralized governance body designs, but it turned out that is extremely difficult to do at low scale. And that's where you have to start out.