I have two questions about the Dream magic chapter of The Mysteries Revised Ed.
A spiritual traveler in a dream, is effectively a spirit with a Might score equal to his Imaginem score (p.106) and may be attacked with might reducing spells and (I guess, though it's not stated) might be kept at bay by wards. What about travelers with an Imaginem score of 0, or travelers who are not magi at all (after all, a magus can bring along other characters with the Road to Lemnos and a non-magus might travel into dreams using a magic item)?
Where are the spell guidelines for traveling/creating portals to/from the Dreamscape?
That seems reasonable, though it does make them extremely vulnerable. Or perhaps all spells described give the traveller a fixed might, say 5, which can be increased by correspondingly increasing the level of the spell (so a level 35 Path to Lemnos would give the caster a Might of 10 etc.)?
No, those Guidelines are about physical travel into a person's dream. I am talking about the Dreamscape (described on p.111), the dreamland "that extends beyond and between dreams", and into which physical travelers cannot enter. While its existence is initially only given as a rumor, then very definite statements are made about it (like "the normal Arcane Connection to the entranced body of the spirit traveler is lost while in the dreamscape"). I wish the author had used the half page left empty at the end the Dream Magic chapter to put in a few more details!