...

If you wish to receive a VINCE notification whenever a different specific vendor receives a VINCE notification, you should contact the other vendor (outside of VINCE) and ask that vendor's VINCE Admin to add your chosen email address to their vendor contact information.  Likewise, if you wish for another vendor to receive a VINCE notification whenever you receive a VINCE notification, then you should add an email address to your VINCE contact list that will reach that other vendor.

What status should I select if my product is end-of-life, end-of-support, or generally no longer supported?

Generally speaking, the same selection criteria used for current products should be used for unsupported products: a product that is vulnerable should be marked "affected," and a product that is not vulnerable should be marked "not affected."  If such a product is affected, mitigation steps should be provided if available.  Additionally, CVE ID(s) should be requested in accordance with https://cve.mitre.org/cve/cna/CVE_Program_End_of_Life_EOL_Assignment_Process.html.