The article I cited about whichever one Norway is stuck into, is that because the withdrawal arrangements of that treaty are difficult, and the Schengen or EFTA rules are arbitrarily decided unilaterally, that it is actually a form of power centralization--a warning that the next step in exploring the concept is incorporating democratic safeguards into international arrangements.
Again, not a denial of concept, just an exploration of the details of implementation (conceptual phase 2?).
Yeah that could definitely be. I haven't done enough research to know just HOW democratic each of these layers should be. But to your point, easy entrance/exit could be one way of making them more so. After all, a lot of the agreements mentioned in this article only work because a lot of countries agreed to join them and make them work. If they don't join, then it is a vote against or for something better.