removing part of concrete slab (balcony)

I agree.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

I would first locate all rebar before going forward, just to make sure the design will be adequate. If drawings are available, either from owner, developer or local building department, get them and verify rebar locations.

Are you removing permanently or just for repair? If permanent, check increased shear at side wall. Negative moment will now be about same as at midspan. If rebar spacing changed along the area, you might run into issue.

Should be fine structurally.
When having them cut re-entrant corners, I typically call for a 3" diameter core drill tangent to the corner, and then tell them to not overrun their saw.
A little more chipping but less risk of unsightly re-entrant cracks that start propagating. If you've ever had to notch lumber that's the analogy.

I would just saw it off without overthinking it. But if you are removing it because it is spalling, you might want to rethink and repair it. Proper repair will probably cost less than replacing the balustrade, and protecting the reinforcement which is exposed by the removal.