Developmental edit for short story (reader magnet)?

I’m an unpublished indie who’s been trying to improve his craft lately by writing a bunch of short stories. And I feel pretty decent about my recent output, with some good feedback from my critique group. So, for a short story that will end up becoming a reader magnet for my upcoming mailing list, would you recommend both a developmental and copy edit?

My “short story” (novelette?) is sitting around 7,500 words. I believe Thomas recommended doing “tryouts” with 3 potential editors to find a good fit, but how many words is sufficient for a developmental sample edit?

Thanks!