Okay, I don't know about the 30V (but that's very bad).

However, for your first (outlet) box:

The 2-wire cable is delivering electricity from the panel. The bare ground wire should be directly bonded to the metal box, and go from there to a pigtail with the bare ground wire from the other cable. Black is hot, White is neutral. All is good.

The 3-wire cable goes from there to the switch. For some odd reason, they chose the red wire to continue the hot run, rather than black. White is still neutral. The Black wire acts as a hot return from the switch to the switched outlet.

At the switch box, the 3-wire cable (above) is delivering electricity from the panel on the Red wire, via the outlet box discussed above.

From here, one 2-wire cable goes to the porch light -- the black for this is connected to the incoming Red (hot) wire. Okay.

The other two 2-wire cables continue the circuit onwards to additional outlets elsewhere.

All perfectly normal, except I would have swapped the red and black conductors (at both ends) for the 3-wire cable. No biggie, the code usually allows either method.

EDIT: As elperepat pointed out, the circuit could be the other way around, with the outlet box being downstream from the porch switch, and not the other way around. This doesn't really affect anything, though, other than which bare ground wire gets hooked directly to the screw on each metal box.

-ml