Emacs offers so many tools for interactive development and debugging that
your first scenario should never happen, assuming you learn what's available
and how to use it. Of the systems in use today, only Smalltalk has better
introspective capabilities. Common Lisp through its Genera manifestation is
superior even to that, but not easily available.

Emacs is the only contemporary widely-used system that can really be
described as an apex / convergence point of stability, extensibility and
self-empowerment. It is the clearest manifestation of "computers are an
extension of the human mind" idea that goes all the way back to control
theory/cybernetics, Licklider ("Man-Computer Symbiosis"), Engelbart, Alan
Kay ..

One reason Emacs is such a rabbit hole, is that it always asks more of
you. It always reminds you, assuming your mind is receptive, of the sheer
potential on offer. Like any iconoclastic technology, it exhibits agency in
that it tempts you to start using it in the way it wants to be used!  And
that's powerful. Very powerful. You're not simply writing scripts to scratch
a temporary itch, but really learning about how to develop strategies to
better manage information. You are expanding your own mind (cybernetic
fusion) and programming the new metasystem at the same time. That's not an
easy problem to solve but perseverance will bring ample reward.

What does it say about the current state of affairs when the typical
reaction to experiencing Emacs for the first time is one of instant recoil
due to the size of the set of possibilities now made available? We've been
so conditioned by tools that operate in A-B-C fashion to expect a
single, well-lit well-trodden path that we become dissonant to an alternative
that opens up entirely different ways of thinking about and dealing with
information.

As to your last point, you can always fire up a new Emacs process and do
your highly experimental customization there if you don't feel confident in
being able to keep track of what's happening and/or worried about breaking
things. Eventually you'll reach the point where this sort of decision is
automatic and seldom needed.