Before they knew the dangers of radium did they use it on darkroom equipment(scales, dials and meters, switches etc)? And how useful would it have been, when the safelight was not used?

Depends on the type of dark room in question :

 - In military applications there was not really "safe light". Any light increases the exposure by some extent, and it would depend on circumstances if it will be noticed by the adversaries and become a target. The glow paint allows seeing instruments and markings only to who is looking at it up close

 - In photographic film processing dark room it's not really possible to do much work in the dark (too many things to be manipulated which don't glow), so a safe light is essential, and with it there is no use to the glow paint

 - In cockpit, monitoring, etc. light in the room is reduced to enable seeing outside in the dark (and not reflections of the inside in the windows), or to reduce eye strain etc. The glow paint helps seeing instruments, but low level general illumination and suitable contrast colors on the instruments may work well too

In many cases phosphorescent paint (which needs recharging) can be a good substitute

The danger of the radium was highly underestimated back then, but the tendency of the radiation to expose the film was quite a strong argument against, I guess. A brief touch of the paper to the dial and the material would be ruined...