I'm in need of a subpanel in the middle of my shop to wire up a few receptacles and lights fed from the 100 amp main panel which is being fed from the house. I have not much experience with wiring as I've only messed with outlets/switches and lights so bear that in mind.
Currently, there is a 10-3 AWG wire (black hot, red hot, ground and neutral) from the shop's panel (it's hooked up to a double-pole 30 amp breaker) to the middle of the shop (30 feet away) where I want to install the subpanel. The wire was ran by my dad years ago otherwise I would have ran new #6 or #8 wire which would've eliminated some of these questions.
The first question: is it okay to use a 10 AWG copper wire to feed from a 30 amp breaker to a 125 amp rated subpanel? I obviously wouldn't be drawing more than 30 amps from this subpanel as it would just be used to wire up my bedroom (tv, low wattage lights, 2 receptacles and a low amperage mini fridge). It would power the tool room with a couple receptacles to charge batteries, run a couple lights and occasionally power up a circular saw. (The bedroom and tool room would never be active at the same time.) The subpanel does say the line A, B and N terminals are suitable for #14 to 2/0 so I figure #10 will be fine.
Second question: would it be okay to have three 15 amp and one 20 amp breaker in this subpanel? As that totals up to more than 30 amps but as I said, no more than 20 amps would be drawn at one time.
Third question: Considering the low amperage power this subpanel would be running, could I simply use a light switch as a main disconnect for the subpanel? Or is a disconnect even needed for a subpanel only 30 feet from the shops main subpanel
Fourth question: does the neutral bar need to be isolated from the ground in the subpanel? It is already isolated, but it came with a bonding strap and ground screw.
Fifth question: Does it matter which hot wires go in to which hot terminal? (A and B)
I think that's about it, any help or tips or advice would be much appreciated, thank you!