Yes it is in 100% working condition. No blank spacebar unfortunately, it didn't come with one.
Not sure about where you can find more info. The black stem is linear, the same as a red switch. The only difference is the force needed to actuate, and then bottom out. The spring. You can take a look at the spring chart I posted to see the force curve.
Clear springs take less force than blacks to initially depress them, but the force needed to bottom them out is slightly more.