Already, you can check it here:http://etherzero.org/index.html?id=2#Exchanges

go to our exchanges:http://etherzero.org/index.html?id=2#Exchanges

You can not send unlimited free transactions. There is a Power called mechanism to prevent ddos attacks.

https://medium.com/@etherzero/a-detail-explanation-of-etherzero-power-value-353c2848e9ae

And also I want to ask that Can we hold ETH and get ETZ in return?

How do they provide safety and security to their users?

wonderful!!

Yes, you can do this:https://medium.com/@etherzero/tutorial-how-to-deploy-etherzero-masternode-step-by-step-adc5e5b08d3d

Due to our Mpos system:
POS:
  The masternode needs to lock 20,000 ETZ and deploy server, providing security economically
Masternode:
The pool of the blocker, is a basic sample of randomness
Random Blocking Committee: Randomly select 21 masternodes each round by using VRF (verifiable random function, random source) in all the masternodes
Limited competition out of block: the use of the committee member seen value (the height of the last block of the masternode) enhance the fork resistance when packing blocks in short time