You do need dc for the Tortoise switch machines, 12 volts is standard. Circuitron (Tortoise manufacturer) sells an AC adaptor (wall wart) that provides 12 vdc at up to 500 milliamps (0.5 amps) that lists at $15.95 but any adaptor that provides 12 vdc with at least 500 milliamps will work - there are cheaper alternatives such as this 12 vdc 2.5 A power supply for $4.95: https://www.allelectronics.com...r-supply-used/1.html
TVS placement is discussed in other threads on this forum. I'd also recommend checking out the PSX-AC which has also been discussed on this forum: https://ogrforum.ogaugerr.com/...ies-circuit-breakers.
Terminal blocks basically can make your wiring job easier and keep it neater and easier to trace when problems arise but they are not "mandatory."
I would not get a separate power supply for powering sidings. You can use toggle switches or Atlas surface mount switches to turn the siding power on and off.