Spindle as speed counter clockwise.

It's an emco lathe encoder
It has index and 150ppr
the 150ppr is connected to phase a
I dont have a phase b

OK, that's enough for threading but not tapping.
If you have an index then there is no reason to change it unless you want tapping (and that's not anything I have felt the need for yet)

If I want tapping function in the future. I need a quadrature right? with Index? How many PPR?

Single-point threading can work with only one pulse, and the 150 you have now is more than enough. Tapping needs to have an accurate idea of exactly when the spindle reverses, so you want to have less space between counts than you can risk mis-rotating a tap by. (and 150 is probably fine there too).

You can single-point most threads that you can tap.