New ceramic brakes ever since they squeak

There's lots of things mechanics do to prevent brake squeals. Did you have the rotors machined? Did you bevel the edges of the linings? Did you clean and lubricate the pad-to-piston and pad-to-caliper contact points? Are the calipers free to slide sideways?

Regular brake pads can make the wheels lock up so there's no need to go to ceramic pads. You won't stop any faster. Harder linings tend to create more brake dust. About all you can do is keep washing it off. If you ignore it, that dust can become hardened and real hard to clean off later. Most brake pads do that now since we don't have asbestos linings any longer.

No danger; just irritating. As a general rule, the higher the quality of the linings, the more they like to squeal. Typically it will be worse in humid conditions, and it's common for the squeal to go away when the linings get hot such as from city driving.

I have a bit different opinion on a couple things here. First off, ceramic pads are excellent quality and highly recommended. They will create less brake dust and are less prone to squealing but as Doc advised, if you didn't do all the additional things that go into a proper brake job, especially the rotors and pad backings, any pad is going to make noise. I expect that your rotors are seriously glazed over and need to be resurfaced or replaced, depending on their condition.

Nobody can know what actually is wrong with your brakes without inspecting them. We can merely tell you what happens when they are done wrong.