It does take about 2 hours time to fully charge the JioPhone's 2000 mAh battery.
No. You cannot use CDMA sim card in the JioPhone.
Yes, JioPhone comes with in-built Facebook Lite Application.
No. JioPhone does not support WhatsApp at least for now. In future, it may support.
Yes, you can use Airtel sim card in the JioPhone but the Airtel sim card will work only on 2G network.