Romance writers are our cousins.
Ghost? = fantasy or horror trope
Premonition? = fantasy trope
Scientific discovery = SF
Not always closely related, I'll grant, but in the ways in which we are shunned by "literature?" Absolutely. We have a lot of common ground relating to publishing, both trad and indie.
sfwa.org
Q: I'm not published yet, can I join?
A: No, but we have programs to help early-career writers without requiring a membership. These include grants, Writer Beware, and mentor programs.
sfwa.org/other-resource…
A: You are welcome. The qualification process is a little involved, but we have a questionnaire to help you decide before filling out the application.
sfwa.org/about/join-us/…
A: They don't need to be. Those are already vetted markets but we have always been willing to approve publishers on an individual basis.
A: Yes/yes/yes/yes
A: SFWA was formed to provide support for professional SFF authors. The membership criteria are calibrated to be roughly the same for our indie as for our trad authors.
We revisit these on a regular basis as the industry evolves.