How to tear down a non-load-bearing wall?

[logic]

Hello,

I am in the process of completely renovating a small studio apartment step by step and have now decided to take down the wall that separates the kitchen from the living room to create a more open layout. I have tried searching around but find it hard to find practical and concrete methods.

The building was constructed in 1939 and the walls apparently consist of about 1.5 cm plaster, with the load-bearing structure appearing to be glued stone. I want to extend the door frame all the way to the outer wall and frame a significantly wider door frame than the existing one.

A few questions:

1. Should I chip off all the plaster first before tearing down the wall? I tested making about a 2 cm wide hole to the load-bearing structure in a few minutes. It goes relatively quickly.
2. How do I break the "glued stone" inside the plaster without damaging the floor? Saw?
3. Can the wall be cut at the height of the door frame or do I have to take the wall all the way down to the ceiling and then frame a new wall section above the door frame?

What should I keep in mind when doing the job if I do it without a contractor?

Thanks a lot in advance! Pictures are below.