1. New posts aren't appearing when I open them (or a user makes them) and they have an exclamation point icon next to them:

Please follow to wpForo changelog and be informed about new features. You should know well the plugin you use. wpForo 1.2.0 comes with built-in Spam Control and Topic/Post moderation functions, also we recommend to install Akismet for more protection, and for making wpForo Spam Control more intuitive.. It keeps new registered users (up to 5 post) topic and posts under hard control and makes those unapproved if something wrong is suspected. You can approve Unapproved topic and Posts in Dashboard > Forums > Moderation admin page.

Please understand the topic/post moderation process before disabling it. It's made for you and for your forum protection and it only works for new users not for all.

Only new users' topic and posts are being suspected for spam and go for moderation. New user is based on minimum number of posts. You can manage it in Dashboard > Forums > Tools > Antspam admin page.

If you test forum with fake users and fake content you'll always see those topics and posts as unapproved. Please teast it with real users and real content (don't duplicate them). If you still got many unapproved topics/posts please read this support topic to decrease spam controlling level:
https://wordpress.org/support/topic/new-topics-and-post-without-moderation/#post-8977005

2. Posts from as early as a few days ago show in the forum index show the last post in the thread at "47 years ago". http://www.cappersinfo.com/forums/nba-basketball-picks/

I don't see such problem. It only can be if the topic/post date is not inserted in database.

3. All my forum indexes have "Guest" listed under the post title (but are credited to a user).

Not sure what is happening here....and I don't know how to resolve..

I don't see Gusts. is this is an imported forum? Are you sure all data where imported correctly? Please check the database before considering it's a wpForo bug.