What is a ‘releve annuel de la CAF ou de la MSA’ and an ‘Avis d’imposition’?

My husband and I registered our B&B as a micro-enterprise in March this year.  My husband is the Director and I am the Conjoint. He has paid 3 quarters of cotisations to date. Neither of us yet have the Carte Vitale though we do have a Mutuelle Bleue online account for the regime obligatoire and can see that we have been reimbursed once into our joint bank account.

As we are British and with Brexit looming, we have decided to apply for the Carte de Séjour Europeen whilst we are still part of the EU to give us the best set of rights here if there is no deal. We have our appointments in 6 weeks time, a day apart.  I (the conjoint) have the first appointment. The Prefecture gave us both the same list of documents to supply at the time of the appointment. 

Please, could you tell me what the following are and how / where we both go to get these / exactly what we should supply?  As micro-entrepreneurs, I thought we do not need to pay ourselves a salary and our understanding is also that we do not have to submit our first tax return until May 2019, hence not having done anything at all about ‘impots’ yet. We have an extrait KBIS but only my husband’s name is on this. We have not yet been here a whole year.

Thank you very much in advance. We really appreciate your help.

1. Justicatif du Droit au sejour: bulletins de salaires, attestation de presence dans l’entreprise, avis d’imposition.
2. Attestation d’assurance maladie [my husband has a ‘Notification d’affiliation a la Securite Sociale pour les Independents but not sure this is the same thing and I don’t have anything like this with my name on currently].
3. Relevé annuel de la CAF ou la MSA [we have absolutely no idea what this is!].