If you want to your sign as a raised letters you can get away without the bridge in the zero.
You may want to experiment with the angle based on the thickness of your blade and which way you go.
I think it is clockwise on the inside and counter clockwise on the outside.
Don
Yes, you must "build bridges" on O's, P's, R's, A's, B's 9's, 8's 6's, 4's etc. How you do it is up to you, there are several ways to go about it. Just look at some stencil fonts and you will notice that again there are several ways to "skin this cat".
As for direction for cutting the inside or out side to get a taper for inlay, it all depends on how you tilt your table (or head). If you tilt the table left side down, cut the inside "clock wise" and the outside "counter clockwise". If you lower the right side of course, you do it the opposite way.
Hope that helps... Rog
And of course the all important "50"! .....Look closely, you will see a 50!
Rog