So, I am thinking of renting an Airbnb for 2 weeks. Is the duration of 2 weeks sufficient so that my visa is not rejected?
The best way to prevent any doubt is of course submitting proof that you have been accepted for student housing by the CROUS but you won't get that now if you haven't applied in advance. It's possible to get a visa without it but it does make rejection more likely.
Various websites (etudes-en-france.info, studely.com, croos.fr) imply that you need to submit evidence regarding your accommodation for the first three months but I haven't been able to find any high-quality source or official website confirming this. VisaYnou published a long discussion of the issue. It's not an official website either and I cannot vouch for them but their advice sounds reasonable.
In particular, they explain that arranging some short-term accommodation to start with and look for something more long-term can be accepted but if you don't have accommodation for the whole year, it is recommended to write a letter explaining why that is and how you will find one. Two weeks might be OK in some cases but both the costs of your initial hotel / AirBnb and your plan to find accommodation must be commensurate with your means, otherwise you risk a refusal.
Should I pay for the Airbnb while living in India or I should pay after I land in France?
Does AirBnB give you a choice? In my experience, you have to provide a credit card when booking, exactly when the charge comes through depends on the host's cancellation conditions.