does this mean an additional download, re-download and install 1847, update license file, MP00?
Topology Optimization is an Add-On and exists as a separate installation to NX, so you'll only have to download the Topology Optimization files and follow the installation instructions so that NX can read them. If you don't already have the increment in your license file for Topology Optimization, then yes, you will need to obtain a new license file.
Will that be in the "Add-Ons" section of downloads?
Yes. Since it's compiled for NX 1847, when it becomes available I would expect it to be located under "NX 1847 Series":
@BenBroad mentioned that it will be an addon for download.
AFAIK, that is not up-to-date information. Starting with NX12.0.2, it is included in the Standard NX Installation.
However it needs to be activated using custom_dirs.dat.
It is located in the Subfolder "TOPOLOGY_OPTIMIZATION" of your NX Installation.