There is another IDENA thread and is way more active:
https://bitcointalk.org/index.php?topic=5194871.msg55749679#msg55749679Back to your questions.
You are solving touring test to prove network that you are human - not bot. That in front of your node stands real, unique person. That's the end of creating your IDENA identity. All idena needs to know about you is that you are not bot and you own 1 node. Then you are able to mine/vote.
According to privacy comparing IDENA to coins like monero. Idena is not anonymous, you can track transactions like on etherum or bitcoin.
Well, but everyone can run as much nodes as he has VPS, right (as no any personal data needed for prove your identity)? So how do they prove this? And what sense in this at all?