A: We are all dreamers and ideally dreams should be accessible to everyone. Being the complex creatures we are, however, no unqualified "yes" can be given to the question.
The one and only purpose of a dream sharing group is to provide an opportunity for people who have a genuine interest in their own dream life to follow through with that interest. It involves a willingness to share of oneself and to help other do the same.
Motive is very important. If that motive is to address personal problems at work or in relationships, more than a dream group may be indicated. Some people, out of ignorance or anxiety may seek outs dream group in lieu of facing the need for formal psychotherapy. There is generally no problem in being in a dream group concordant with therapy. The combination can function in complementary ways, with each able to give the dreamer something special. The dream group is not an alternative to therapy when therapy is indicated.
Some people would genuinely like to connect with their dreams but have great difficulty in recalling them. Dream recall is a variable thing. Being in a social context where dreams are considered important can be a stimulus to recall. Being in a dream group over a period of time can increase the yield of dreams.
A less frequent source of difficulty is what a Norwegian colleague of mine (Jan Tolaas) called "metaphor blindness." Some people tend to be so literal and concrete in their thinking, so linear and logical, that the shift to the more abstract metaphorical mode presence a problem for them. I have seen them make progress in a group if their motivation remains high.
A: The arrangement I make with the people entering my groups is for four weekly sessions, renewable for four weekly periods as desired. Within this period of time a new member usually discovers whether the dream group is suitable or whether more (i.e. psychotherapy) is needed. If no, I would offer my recommendation privately at the end of the four-week interval. People differ in their readiness for group dream work. Psychopathology in and of itself is not a contraindication for pursuing dream work if there is also a genuine interest in dreams. Group dream work brings out the best in people.
A: Eight is ideal - from five to 10 is workable.