Hi @christopher,

Please see my answers below:

If I install wpDiscuz and wpForo, they both handle commenting and private messaging. Which one gets management of those items if I have the "Blog Cross Post" plugin for wpDiscuz?

Each of them manage their part. Blog posts and blog post comments are under wpDiscuz control, the cross-posted Forum topic and Topic replies are under wpForo Control. You can edit and delete those separately without affecting other side. But you can edit and delete those synced from any side. For example if you delete a comment from blog side it can be deleted in forum to... All these depend on following options in the Cross-posting addon:

I plan on purchasing the $99 wpDiscuz package of all plugins, as well as "Blog Cross Post" for wpForo. Do I also need the Private Messages plugin for wpForo?

As you know Blog post is cross-posted as forum topic if you use the wpForo Cross-Posting addon. And Post Comments are cross-posted as the Topic replies. Please note, that the wpDiscuz Private Comments addon cannot create private replies in cross-posted forum topic. This addon is designed only for the comments. You can create private comment threads. The comment thread will be cross-posted in the cross-posted topic as public replies, because only the whole topic can be private in wpForo forum, there is no way to set one reply private.

wpForo Private Messages addon has no any relation to private topics and replies in forum. This addon creates a messenger in profile page of forum members and allows them to send private messages to other forum members. So if you want to allow forum members to talk privately with each other you should buy this addon too.

I was going to use Restrict Content Pro, but they are lacking some features I need, so now I'm considering other options. Do you guys know of a good membership package that integrates well with wpForo?

Here is that well explained: https://wpforo.com/community/wpforo-integration/new-to-wpforo-asking-about-specific-integration-before-buying/#post-35577