Which one of these 5 pin 3 phase connectors is more standard?
Either two of them, the difference is in rated current 16A or 32A. Usually the 32A is well suited for a medium/small machine, the power connected is 32*0.4*1.73 &lt;= 22kW, while the smaller one is more frequenty in use, because is the minimal 3 phase connector, therefore all hand tools, small electric machines, P&lt;=11kW goes on 16A connector. The conclusion is: probably you wil need more 16A connectors.
The 3ph+N, what you are reffering is a 3PH+PEN, it's normal in most places in the world, in EU also. At your main cabinet you should split this PEN wire into two wires PE and N. The distribution network is never 2PH+N+PE, you won't find this enywhere, its not a Soviet madness.