Yes I did get a free one from Boat US so I guess it's a US only MMSI.
Yes I don't think the SSB has a DSC feature.
I imagine Docksideradio.com can help me iron out the MMSI issue. Right now I am just trying to get a hold of the PO so he can release the Boat's FCC license so I can get my own.
I don't think the PO has to "release" the boat's FCC license. You can and should get your own Ship Station License, on the basis of new ownership.
You also need to be sure to "check all the boxes", as noted above.
You should also get a new FCC-issued MMSI number. This can be done at the same time as the Ship Station License. It is THIS number you should have programmed into your transmitting equipment, not any other. FYI, most VHF/DSC radios allow you to enter the MMSI number twice, but not more. Some radios only allow a single entry, after which you would need to send the radio back to the dealer for programming.