[Jerander]

Do people enter the Dream World physically? Or is it a projection, leaving the body behind?

Entering the global Dream World requires abilities/technology. Would passing from region to region also require the ability/technology?

If projection, my first thought is that every individual has their own doorway through their personal dreams. Groups could be brought into the global Dream World in the same spot through the use of an "artificial" group "personal" dream. This staging area could be set up either through technology or other means. The TV show Supernatural allowed group dreaming (or at least entering someone else's dream to share it) through the use of "African dream root" and close proximity and/or contact. Something similar could allow you to keep the party together.