Google it :)

No, but they do have some information about the restoration posted along the barriers. It was interesting to walk around the cathedral and read about the fire and the plans to rebuild.

La visite est totalement interdite suite à l’incendie

Checked for you last night, no special lights. Very dark and sad. May have been in mourning for president Chirac, but I don’t think so.

Notre Dame will be closed for renovation and repair. Mass will be held at St Germain d'Auxerrois, near the Louvre museum, with the Archbishop presiding Sunday evening, I couldn't find information about the mass in English. concerts will also transfer to this church,

It is a definite NO. You can take a river cruise and see the back of the building from the river but it will take YEARS to renovate. There are plenty of other things to visit. Take a hop on hop off bus tour, there are several routes and you see a lot.

Highly unlikely. Nothing can take place *within* the cathedral because of current lead abatement from the once glorious lead roof over the cathedral. I am fairly certain that the Crown of Thorns (along with other treasures) were rescued from the cathedral during the fire, but they are now safely stored off-site until the cathedral is safe for re-entry.

yes.

Leider kann man die Kathedrale nur von weitem betrachten.

You have to get in before 6ish.