Hi Ezequiel
Regarding your second question, and what Celeste explained, the flag "User Self Registration Component" means that, once activated, you won't be able to 'replicate/send' vendors from MM to SUS (as an initial load). Then, the process continues that they will receive an email to complete the creation of their user.
You will be able to create vendors in XK01, but won't be able to send to SUS from MM once that flag is activated.
Regards,
Martín