2) What would prevent somebody to create an exchange, keep it running for some time to make it "legit" in Inchain point of view, and then put all his coins on the its own exchange with many different accounts, take Inchain insurance, scam/close his exchanges ( he also necessarly still have his coins) and then ask Inchain for his compensation with each account?
There will be a limit to how much Inchain will insure each exchange for.
Not sure if it can be prevented but it will limit the damage that can be done.
Considering the amount of work that will need to be put in to such a scam vs. the payout, I doubt it will be a very common scam. Also with KYC it will be much easier to open and exchange and steal peoples money that way without trying to do insurance fraud aswell.