Well, the new url would cause a slowdown until things start getting crawled; you could try a sitemap and feed urls to google (you could make one manually, or with a 3rd party script such as my sitemap script (see signature).
even witha sitemap, a new forum is going to take some time to get some momentum going, but you'll definately get there once things start getting indexed.
as for the settings, you'll want to keep all of those on, they're stopping bots from registering; by disabling them you're welcoming bots and trolls in.
