1) Yes, I would have put at least 20A Breakers in. My Chassis are powered via a 30A PDU on a 30A Breaker, though its admittedly a bit overkill. 20A is a pretty safe bet to stick with. Last thing you need is to trip your breakers whenever your servers go under load.
If you take the Power Backplane out on the 3 phase units and take it apart (This may blow your warranty so you may just have to take my word for it), the two lines are attached to 3 of the PSUs each.
Line A connects to PSU 1, 2, 3 and Line B connects to PSU 4, 5, 6
All the 3 Phase Backplane does, is hook up the first phase and common to 1, 2nd phase and common to 2, 3rd phase and common to 3., and the same idea for Line B and 4, 5, 6. There literally is no electronics or regulation circuitry etc built into the backplane. Just a direct wire to each PSU. This gives each 120V phase to the PSUs. (Also why a Phase Emulator will only replicate 2/3 phases, and subsequently only power 2/3 PSUs). The PSUs are able to handle both Single and 3 Phase.
2) I dont know the answer to this
3) Yes, to prevent tripping your breaker. HOWEVER, know that you will be capping and restricting your Blade's performance and it may not be able to ramp up to the expected speeds to do its job efficiently. Its much better to put the proper breakers in the first place.
