Current limits and sensors power consumption
Referring to the first datasheet, 

Looks to me like 200mA (Effective operating current Ie) is the maximum load current through the output (PNP) transistor. Bemessungsbetriebsstrom is "rated current".

6mA (No-load current Io damped max.) and 3mA (Max. no-load cur. Io undamped) are the maximum power supply currents depending on whether it "sees" metal (the internal oscillator is damped) or not. This does not include any load current, of course. Diagram from here. 



Off-state current is the maximum leakage of the PNP transistor (in other words if you need the output voltage to be less than (say) 0.4V, you should use a load resistor of less than 5K). 

So, your power supply current for eight sensors should be 8 times 6mA = 48mA plus whatever the total of all loads adds up to. 

With a 500mA power supply you could have >50mA per load. 

I have no idea what "Short circuit current 100A" means, it really seems like it could be a typo. Most such sensors from reputable makers have some kind of short-circuit output protection, but 300mA~1A would be more like it. Nothing like that number appears in the current catalog here.