Anodized items are generally dishwasher safe and scratch safe from other metals. It does depend on the process and quality of the anodizing though. However, 36 bucks for a small tray to hold "something" with no magnets, I mean, there's just no reason for these to exist.
I had the same question .. and by the looks of the photo showing the bottom of the square one, it doesn't look like it would nest securely when stacked. Would love to hear someone in the know to confirm.