Now that two plugins are combined ("Latest Replies" combined with "Add Titles to Replies") do I need to make any template changes.
No, not at all, the two plugins have literally just been plumped together. All you have to do is delete the old "lastest-replies.php" plugin to avoid conflict.
I'm using another plugin to cross-post WordPress posts to bbPress topics, but it doesn't seem to work with this plugin, why?
Probably because we have added an extra field to the database that your cross-post plugin does not account for. For now there is no solution, but it is being worked on.