How do I apply saved Session Settings to new Sessions?

Just open your saved session and change the paths. If you want to keep the new session, you'll probably want to save it with a different session name.

After editing session settings, you can use the dropdown at the bottom of the Session Settings dialog to update your session defaults, so that those changes are automatically applied to new sessions.

Regarding the second part of your post, you might be interested in the work-around suggestion I made
in this post in response to another user's request to support Session "profiles".

Thanks for the replies.

@Erik
This method has two drawbacks. The first is the risk of accidentally saving before having renamed the session, which would unintentionally change the settings of the original session. The second is a matter of maintainability. Once you have a several sessions with different settings, it's rather cumbersome to change a specific setting for several of those sessions.

@Michael
Obviously, updating the session defaults is not what you want in many cases. The post you refer to is interesting though. I had been experimenting with a similar approach already, but the tips for clearing the file list and loading a 'profile' are welcome.

Hopefully we will see a robust, native template/profile mechanism in a future version of BC3.

If you edit the Session from the Home Screen, the buttons change on the bottom to use it as a Template (with the default becoming Open As New).

You could create a Folder of "Template" Sessions in your Home Screen, and alter them before Opening them as New, or Save As.

Another valuable tip. Thanks for that Aaron.