You don't need separate toggle switches for each signal unless you want to switch them on/off. Just hook them up to your DC supply. For example my AC and DC supplies are activated when I turn my layout ON. My turnouts and signals are wired directly to my AC and DC supplies and thus are always ON when my layout is ON. I have toggle switches downstream of my AC and DC supplies to control accessories as desired.
If your anticipated DC power requirements are modest, leftover wall warts may suffice. If your DC requirements are more extensive you might considered a larger regulated DC supply. Regulated implies it should be a high quality filtered supply outputting pure DC (ie flat line, no ripple). I use a 33 amp, 12 VDC supply I purchased from Micro Mark for around $60: https://www.micromark.com/12-V...ieaje-QaAlfQEALw_wcB . Like wall warts, larger DC supplies may require 110 VAC input. You must observe polarity when using DC supplies.
