Yeah, mine was run from the black box. Told the installer I don't have one of the grey boxes and he said it was not a problem. They did seem to have about 10-15 minutes of troubleshooting but no major issues.
You can sign up with any ISP if there is fibre in your area.
If there is no fibre then most ISPs allow you to sign up to be notified when it does become available. And that will be once vumatel/openserve/etc let all ISP know that the fibre in the area is ready for deployment to interested parties.
Vumatel. Usually uses the website as reference for interest as people use fake address etc. But you will need to get actual 30% of the neighborhood. Then they would need to get funding from investors and then a go ahead from the city of Cape Town. Southfield and Elfindale took around 6 - 8 months from start to finish