Auto entrepreneur registration issues

Hi, I completed my registration for Auto-Entrepreneur on the autoentrepreneur.urssaf.fr site a couple of weeks ago.

I have received through the post:
- A letter from INSEE with my SIRET/SIREN number
- A letter from URSSAF with my Sécurité Social number
- A letter from Finances Puliques asking me to register on impots.gouv.fr, a form (751-SD) asking about where I work (How many sqm I use at home) and a Cerfa 1447-C-SD Cotisation Foncière des Entreprises 2023.

I have just created the account on impots.gouv.fr and await an activation code through the post.

Q1 - When I log into autoentrepreneur.urssaf.fr it asks me “Veuillez saisir votre numéro de Sécurité Sociale (13 chiffres) ainsi que la clé (2 chiffres)”. The number I have is 13 digits, so I enter the first 11 followed by the last 2 as the key but I get an error “La clé ne valide pas le numéro de Sécurité Sociale”. Am I doing something wrong or does it take a while to flow through the system?

Q2 - I’ve registered on the INPI website, but nothing shows there. Do I have to go through the Business Creation section, or will my business just appear there over time? I’m not sure it asked me specifics, so don’t think it will. Or do we just continue to use the autoentrepreneur.urssaf.fr site as that’s where I initially registered.

Q3 - What is the Cerfa 1447-C-SD (Cotisation Foncière des Entreprises) form for? Does this relate to the questions on the 751 form asking how much space I use at home for work?

Q4 - We kind of expected this, I registered as my wife being a conjoint but have received nothing at all for her. As a conjoint, should she also get her own SS number and what about SIRET, will she get her own or do we share one? What is the process now for me to get her setup as a conjoint?

Many Thanks