1.1) 30 amp circuit might be OK, 40 amp might be safer to prevent nuisance trips on startup. The Delta manual suggests a 10 amp breaker for the drives
1.2, 1.3) I normally use one breaker for each drive and power supply input. UL 1077 breakers, C curve. So that would be four 10 amp and one 30 amp breaker for the drives, and one 5 amp for each power supply.
2.1) One 10 amp contactor for each Delta drive, and at least one ice cube relay for the E-stop/control power circuit. Normally you would use contactors/relays with 24VDC coils.
2.2) I normally use a rotary switch for the main panel disconnect, or use a seperate main disconnect on the wall.
Handling the alarm shutdown could be done through another relay and as part of the E-stop circuit. I normally add a provision for a controller generated E-stop via an E-stop permissive relay. The controller is a lot faster than you are. But under no condition would you allow the controller to energize the control power, it only allows the control power to be energized by you pushing the control power button. In other words, if the controller is happy then you are allowed to energize the control power.
Here is a 2 servo panel, 230V, single phase panel I built a few weeks ago for a non-CNC project. One breaker for each drive, one breaker for the 24V power supply input, one breaker for the 24VAC transformer input, one preaker for the 24VDC output, and one breaker for the 24VAC transformer output. In this case I had a need for 24VAC on the machine, normally would not be found on a CNC machine. There is no controller in this machine.
Here is the main power schematic