It's not a very easy process, but I don't think it much matters whether the text is extruded or not.
You can have zero-thickness text or graphics on surfaces. That's what the Split Line and Wrap functions give you.
I don't think you need to do that. When you pattern your buttons, you can also pattern the cuts, so there is only one feature added.
Well, almost. Keypads are usually compression molded out of silicone rubber. We tried injection molding a keypad out of polyurethane, but the urethane was too stiff at cold temperatures and it was very difficult to injection mold the very thin walls that you can get in compression molding.
But that is a very fine distinction. The design rules for compression and injection molding are not all that different.
So, what
It depends upon the part. A case part is typically done from the outside in. You generate the basic shape, then shell it, then add the bosses, ribs, recesses, vents, holes and other features that you need.
For a keypad, you might want to go the other direction or not. In the old days, before multi-body parts, you would probably make the flat bottom piece as the first bit, then add the buttons. I would probably be inclined to go that way still, just because the feature scope often gets lost on multi-body parts and causes unexpected errors to show up later on.
Jerry Steiger Tripod Data Systems "take the garbage out, dear"