Hi,

One question: if my UTM coordinates in 3 zone width (0.9999 scale). How to reduce to this one?

The zone width is defined to 6°, cf. UTM zone definition. If you have a special (local) projection, you have to reduce the distances by your own, defined by your special crs.

Please note, all projections are applied only to horizontal distances (but not to slope distances!).

/Micha