Conservative preparation
Enamel that does not need to be removed is not removed. What remains is what bonds.
Porcelain veneers
Veneers that read as natural are the ones whose proportion, length and shade value were decided against a face rather than chosen from a shade tab.
The porcelain available to any dentist is much the same. What differs is how much tooth is removed, whether the bite was analysed, and whether the shape suits the face it sits in.
Enamel that does not need to be removed is not removed. What remains is what bonds.
Value, translucency and surface texture are read against skin, lips and the eye, not against a tab in isolation.
A veneer that looks correct and takes the force of a bite it was not designed for will fail. That analysis happens first.
The preview
You wear a physical preview of the proposed smile and approve it. Changes are made in that preview, where they cost nothing, rather than in porcelain.
Questions
Not when preparation is conservative and the bite has been analysed. The damage people describe usually comes from over-reduction, not from veneers as such.
However many the design requires for symmetry, which is often fewer than expected. It follows the analysis.
Yes, and length is one of the main levers in smile design. How much is right is decided by lip position and how much tooth shows at rest.
No obligation
The preliminary consultation is free and includes a 2‑D panoramic scan. If the plan you were given was the right one, you will be told so.