Thanks a lot for your help. I'll go over this all again asap and give something a try. I'll report back with how it went.You can't copy the "Install macOS Sierra" app from the HDD to the SSD because of new Sierra install app bug. If you try to launch it from SSD you will see:
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You must run the "Install macOS Sierra" app from the Applications folder that InstallOS.dmg (downloaded in Step 4) and InstallOS.pkg (Step 5) was run on to create the "Install macOS Sierra" app in the Applications folder (I would recommend NOT rebooting before running the "Install macOS Sierra" app). You can select the disk to install Sierra on once you launch the the "Install macOS Sierra" app and see the window shown in Step 6 and click Continue.
If you want to do a clean install, that is more complicated because of the buggy new Sierra installer.
I would recommend booting from an El Capitan USB installer. Erase the drive you want to do the clean install, install El Capitan to the wiped drive, create your login account, boot from the new account on the freshly installed drive, then run the Sierra InstallOS.dmg (downloaded in Step 4) and InstallOS.pkg (Step 5) to create the "Install macOS Sierra" app in the Applications folder. Launch the "Install macOS Sierra" app to install Sierra. That is as close to a clean install that I can think of because the bug in the Sierra installer.
You could create a working Sierra USB installer IF you had the old Sierra installer before the certificate expired, but Apple does not provide that for download any longer.