Yes you are right the idex exchange like a decentralized for example like etherdelta and livecoin is like a bittrex or polo and more exchanger if you want to exchange any tokens at idex there are some videos about that at youtube.
thats right, idex is like Etherdelta. if you wanna trading in Idex you can import your privkey or you can create new account. to trade in idex its not simple like livecoin because this is decentralized exchange, but is good because decentralized exchange is more safety than centralized exchange like livecoin.