Questions about Works in Progress

Although it's not in the submission guide on the normal IMDb site, the release date submission guide on IMDb Contributor says this:

• Public festival work-in-progress screenings are accepted with the festival name and the additional attribute (work-in-progress).

I have two questions about this:

1. Can the (work-in-progress) attribute be used for other public screenings or is it specific to festivals for some reason?
2. Does a work-in-progress screening count as the original release for the credits, i.e. when adding credits, do I use the credits list from the first work-in-progress version or the credits in first normal, finished version?