'The Exorcist' Prequel Details Revealed

Our current, basic understanding of the plot for Exorcist: The Beginning is:
It is a prequel to The Exorcist, set just after World War II, during Father Merrin's missionary work in Africa, when he meets the demon Pazuzu for the first time (as mentioned in the first film and it's poor sequels). Without giving too much away - is this basic plot outline correct?
Yes - this is the basic plotline, however he has lost the name 'Pazuzu' in our script. Just the Devil Himself.

Approximately what year does Exorcist: The Beginning take place in, and how old is Father Merrin?
Most of the action is set in 1947 in the Turkana region of Kenya. There's also a significant flashback to an even earlier period: 1944 in Holland

This project has already had numerous names... Exorcist: Dominion, Exorcist 4:1, etc. Is Exorcist: The Beginning the definite final name for the film?
EXORCIST: THE BEGINNING is the definite final name for the film.

Aside from Pazuzu and Father Merrin, are there any other characters from the other three Exorcist films making an appearance?
Since this is a prequel that takes place in 1947, the characters that appeared in the other Exorcist films would not have been alive. Also, don't expect any cameo appearances from Linda Blair or Ellen Burstyn, Lee J Cobb, Jason Miller or any other actors who appeared in any of the previous Exorcist movies.