Also these questions (I assume) are not rigid "bring a signed stakeholder form to me before we start", its an informal "Mr. X wants this worked on instead of (other thing)?" and they say "Yes". If later it turns out to be inaccurate then the requestor is now the boy who cried wolf and gets vetted much more strictly for future requests. Possibly with a signed stakeholder form before you start.
But the questions are really simple: What's the impact? Is the scope of work agreed asked for by product?
The third question is really their question to their team, what's the effort needed for us to fulfill this ask?
That seems like common sense to me, but maybe I'm missing something. These questions should be answered before even the original asker starts their work.
Being interrupted a lot is less bad than creating a culture where people are afraid to bring bad things to you early.