> What do you do when you don't have a spec and when you ask the senior engineer you are working with questions, they don't respond or push back against having a spec or a plan longer than the very next feature?

What I would suggest is that you should learn the practices of wherever you are working, and not spend much effort trying to change them. Your first couple of jobs, you'll hopefully be exposed to several different methodologies, and only then will you have the experience to advocate for best practices, as well as being able then to speak to evidence of it working at a past job.

> What do you do if asked to estimate how long something will take to debug? What if you just started on a project and the error message you are trying to debug doesn't make sense?

If you can't accurately estimate debugging, instead explain what you understand, what you don't understand, what you've learned so far, and what you're planning on trying next.