I'm not quite sure what you are asking. In order to use this 30 amp breaker safely, a minimum of 10 gauge wire should be used as a feed from the main electrical panel, with a distance no greater than 25'. A number 8 gauge wire is to be used for a distance 26-50'.
Wrong box for your application. This box is used mostly as a 30 amp RV connection.
It's not an Allen , it's a standard TORX lug. You can purchase a multi TORX wrench for less then $20 and it will solve your problem!
No! If you can't look inside the box and identify the connection points where you are going to use 3 10 gauge wires that are connected to the corresponding connection points in your main power panel bus then you need to get professional assistance! You will connect POLE TO POLE AND GROUND TO GROUND between the buss of your breaker panel to the Midwest junction box! This junction box has its own protective breaker so you connect your 10g patch wires drectly to the buss connection lugs of the main breaker box that has the breakers for your home.
You should have a dedicated 30 amp breaker in your electrical panel and run a number 10 gauge wire to the new breaker box, with a distance no greater than 25', or a number 8 gauge wire with a distance 26-50' from the panel. Yes, you will end up with two breakers, just like is used to power your central AC with one breaker in the panel and one near the AC condenser.
Not sure if it is code were you live, but that is exactly what I did to install for my application.
Theoretically, yes. But, your local electrical code will prevail. If I were doing it over, I'd tap the power off a bigger CFI breaker. I basically use the outside breaker for an on/off switch.
#0 aluminum may be terminated with a #6 awg reducer cable crimped to the Power outlet end of your feeder. What is the actual feeder distance? as I suspect you are concerned with volt drop at a max load. Both #6 CU or Al is suitable for 30 amp service at a very significant distance.
With the distance to the outlet at 90 ft, I would use the #8-2 with ground to lower the loss. The outlet comes pre wired to the breaker and outlet. Connect the Black (Hot wire) from feed breaker to breaker terminal, White (Return wire) to White terminal, and ground wire to ground terminal. Then use #10-2 with ground from the outlet to the load.
They are in the bottom