Positioning plugin fields in Admin (post editor)

This is maybe 2 questions. I am using a plugin to add some custom fields to my posts (Membership Level, Target Audience, and Extra Notes). There are other plugins in use that modify the post editing interface with their own fields. In the post editing interface, the other plugins display their fields first, then my custom ones (using Advanced Custom Fields) display after. I would like this reversed.

A) How is the order that plugin custom fields rendered determined? Can I rearrange this somewhere?

B) Since I am using very simple extra fields, would I be better off doing something with an Admin theme, or creating my own plugin that displays itself wherever I choose (if possible)?

Any tips are appreciated.