Questions; Should I direct this installation to my present CouATL location (the FSX folder) by browsing to it, and allow it to overwrite my present version; or should I un-install my present version and then install the new Couatl in a location of my choice
Now the installer is giving you a choice, it's best you don't use the FSX folder anymore, but rather a folder of your choice, which can be either the default (which is fine, if you have enough space on C:), or something else entirely, even on another drive.
The installer will remove any old copy of the Addon Manager, and will update all the files that require to be updated, to comply with the new installation method, and this is valid for Flightbeam products requiring the Addon Manager that you had installed, since the installer recognize them too.
If you have newer Flightbeam installers that don't use the Addon Manager, it's best if you uninstall their old versions first, update all the FSDT software, and install Flightbeam using their latest installers.