Is either the 4.7 or HEAD version compatible with 5.0. If not are there plans to produce a 5.0 version?

Both 4.7 and HEAD are strictly identical and will work with Drupal 5.x if you add an .info file as anexed.

Otherwise, it does work making dates optional in forms but displaying such date shows 00/00/0 in profiles, so this is not very usefull for me and I'm not sure how to deal with this at theme level or else.

Woah, old issue. I've published a new release for drupal-5.x, including your .info file. Thanks.

http://drupal.org/node/722552