1) You can subscribe to forums or just certain threads. So the message can still come into the Inbox of your mail client. If you want to reply to any of the messages, just click on the link in the body of your mail message. Dead simple, and you don't need to remember to go to the forum all the time.
2) The main reason for setting up the forum: it won't clutter the C-L mailing list. I know there is a lot of excitement about this project and it's great to see some enthusiasm on the list, but I have to be careful about number of messages. Otherwise we get a bunch of unsubscribes. I don't want that.
3) We could limit access to the forum to just the people working on the project.
4) You can use the forum tools to help one another. Rookie constructors can post entire puzzles in .puz or.ccw format, or can post an image file of just one section of a puzzle, then ask for advice. If the forum is private, the public won't see.
5) There is a polling feature. This will allow the group to vote on any particular issue that arises (how payments should be made, what publishing company to use, etc.).
Please give it a try and see if perhaps modern forums aren't such a bad thing, and maybe even a useful tool.