Question about adding SSD to my 2012 MBP (non-Retina)
I am not familiar with that particular SSD, however if it is a standard form factor 2.5" SATA drive then it should work. This take apart on fixit.com shows replacing the HD in a 13" 2012 MacBook Pro.

I don't know where you heard that Macs can't boot from an optical drive but that is patently false. macOS used to come on optical media that you had to boot from to install  the OS. Also many repair utilities came on optical disks that you booted from.

Technically speaking it is possible to replace an optical drive with another kind of drive (SSD, HD, etc.) and there are a number of places you can find the instructions for this specific thing.

IfixIt would be a good place to start, I think they have a kit that adapts the optical drive bay to another kind of drive. Try MacSales too. I seem to recall they carried things like this.