How easily do they come apart?
Easy and not at the same time. The one I've got graphics seem to be on sticker and not on a loose piece of paper. I'm not gonna pull off though to make sure. Other than that I like it a lot. Once powered they give very nice bright light.
You didn't mention what kind of button you are referring to.
The GGG buttons look like standard rectangular button with an insert that looks like a coin slot.
http://www.happcontrols.com/pushbuttons/5400045x.htmDifferent colors are available obviously. (red, white, blue, green, yellow, amber)
Keep in mind these look to be installed just like any other button, not directly in a coin door without some modification to the door itself I'm sure. (removing coin mech assemblies, etc)
As for the inserts themselves...... I just make my own anymore.
Can modify them to say whatever you want.
To replace them is easy, either the cap pops right off, there are two tabs to release the top, or there is a simple lot to slide them in, all depend on the type of button/coin button you have.