How do I make an outdoor house number or address sign: which material, and V-carved or raised numbers?

Choose the material first

Outdoors, the material decides how long the sign lasts, and it changes the settings.

PVC trim board is the most recommended choice in maker discussions: waterproof, paintable and sold at home centers in several widths.
HDU sign foam is what professional sign makers favor for larger outdoor signs.
Color-layered HDPE needs no paint: cutting through the top color exposes the core.
Wood works with primer and exterior paint (one maker used poplar), but the same makers rate PVC better over the long term.

V-carved numbers are fast and need one bit. Depth follows stroke width, so large numerals can go deep. Check Flat Depth in the V-Carve toolpath to cap it.
Recessed flat numbers (a Pocket inside each numeral) give a level floor that paint-fills cleanly.
Raised numbers (a Pocket between a border and the numerals) read well from the street but take longer and leave a large floor to finish.

Measure the board and set up the job. Draw the plaque outline and the numerals in a bold font.
Mask the face before cutting. One maker uses clear shelf paper.
Pocket the numerals. A reported PVC recipe: single flute bit, about 18,000 RPM, feed 80 and plunge 24 inches per minute, 0.100 inch per pass, 0.190 inch total. The goal is chips, not melted plastic. Test on an offcut.
Profile the plaque outline with tabs, then drill or pocket any mounting holes.
Spray the recess color, peel the mask, and roll the face color with a foam roller. At 0.190 inch deep the roller does not reach the recess.

Before painting PVC, scuff the surface and wipe it with wax and grease remover so paint bonds.
Add keyhole slots or mounting holes in the design stage, not after painting.
See the entries on HDU sign foam, paint-filling carved lettering and raised-letter signs for each variation.