I'd say the organization is quite well known for being incredibly notorious for the reasons you have already mentioned. It's quite pathetic how they remove the Camelot brand from their listings, because its reputation is so tainted. Both locations you mentioned are part of the Camelot Campus 015.
If you're in for some fun these and these reviews are quite the rollercoaster. My favourite review was the one where the night guard came over to check that nobody was sleeping over for more than 2 days in a row, or that guest parking was 25 euros for more than 30 minutes. On the bright side, apparently the rooms themselves aren't that bad (minus the heat/walls), just that the experience itself significantly outweighs the benefits of a decent room.
That being said, I don't know anyone personally who has stayed there. A friend of mine knows a few, and as far as I know everyone of those are moving out as soon as their contract allows them to do so. Keep in mind that they will give you a 12 month minimum contract, so if you do opt for Camelot, you're stuck with them for a while.
My advice: unless you have no other choice, stay away.
I don't really know what you mean, public health insurance isn't a thing at all in the Netherlands, it simply doesn't exist, also for Dutch people. You can only get private insurance.
However, all insurers are bound to strict rules. For example they have to offer the "basisverzekering" (most basic insurance plan) for the price laid out by the government. Also companies can't deny anyone wanting to take out insurance, no matter any pre-existing conditions.
If you had Googled a little bit you'd know, there's hundreds of pages about this, for example:
https://wise.com/us/blog/healthcare-system-in-the-netherlands