Brake squeal is caused by vibration of the pads (or shoes) against the mounting plate or caliper, and can be caused by vibrating against the rotor or drum.There are pasts or creams (for lack of a better description) that will dampen the vibration that can be used on the surface where the pad or shoes come in contact with the mounting surface, or sometimes a shim is used.
Also once the material the brake is made of gets hot, it will harden and also can cause noise. sanding the mounting points, or roughing the drum (or rotor) will also change the vibration pattern and interrupt the vibration. It will wear smooth after a bit and the noise will return.
Replacing the rotors or drums will also change the vibration and changing the pads or shoes will do the same. Different materials handle the generated heat differently, ceramic handles the heat the best and is better at reducing wear on the pads. It will however cause more wear on the rotors so they may be worn past their service thickness and need replacing sooner (after a set of pads or 2) Most newer rotors and drums are much thinner than the old school ones and so the common practice of resurfacing them has been replaced with installing new ones. The coat of replacement parts is usually the same as turning them down or resurfacing them.
Ceramic pads will give you a cleaner brake (and wheel) and a quieter sound when stopping. they resist heat and will stop better without fading on extreme stopping , not that it is really needed on most smarts. Slotted or drilled rotors will also help with keeping the brake temps down, again not really needed on a smart, but they look cool...The dust generated by the brakes and that coats the wheels is a necessary evil as the rotors and wheels are designed to draw the dust away from the brakes and keep them cleaner. Unfortunately the dust is hot and tends to stick to painted or clear coated wheels.
There are different ceramic pads, and you want to get the ceramic ones, not the composite ceramic pads. those use ceramic and organic mixture to aid in stopping. Also creates more dust than the ceramic alone. If you are doing the brakes yourself, pay extra attention to cleaning any rust or dust buildup on the components and only use lubrication on the mounting points designed specifically for brakes. standard grease will turn liquid at the temps that are present in braking and if it gets on the braking surface, you will not stop!! use it sparingly.
brake noise when you first take off in the morning can be caused by what they call 'flash rust' the rotors will get a small amount of rust on the surface from cooling gown after use and sitting over night (cooler temps) Not much can be done about this except trying a different brand of rotor as some are more prone to this than others depending on the material they are made of. This 'flash rust' doesn't really affect anything, just makes a bit of noise when you first use them. Once it gets worn off, they are quiet again.