Thank you for all of that.
This is an important nugget! and it’s why getting research experience is so key to PhD programs- it’s part of making sure that you like doing the kind of research that is involved in a given field. What sort of ‘work environment’ are you envisioning? Fwiw (random sample of 1!), the researcher I know at UWa basically works in an office/lab setup.
100%! It’s why one of the Collegekids ended up as a physics major and not an astrophysics major…
PhD programs will be more interested in research experience, while an internship will help you learn more about how much you like that environment/work. Of course, if the internship gives you specific skills (ability to use software or equipment important to the work of researchers at the place you apply to do a PhD, for example) it can do both. Have you talked to your advisor about the specific research opportunities available to you at your college?
tl;dr- are you more interested in the where (astro) or the what (nature of living organisms)? That’s your major.