Livret de famille

Hi Sneha,
Certainly you want the livret de famille ; it shows all your family relationships. eg, mine shows my French husband's parents names and birth places, his birth info, and our marriage. It also shows my birth info. It means that France recognizes (very officially) your family status. When you have kids, the go in too.
You get your marriage added via the consulate where you married (Mauritius, in your case). I forget exactly how long it took for mine (we weren't in a hurry).
I'm not sure if it is really required for you spousal visa, as long as you have your marriage certificate; best to check the list (I think it will just say proof of marriage, and you could provide either).
However, it is worth getting it going before you leave Mauritius; as long as you have a long term address in France, they will send it on to you.
bonne chance,
Julie