It takes about 2 hours time to fully charge Vivo S1 battery from 0% to 100%. Please note that Vivo S1 comes with a huge battery capacity of 4500 mAh. Hence despite fast charging support, it takes a little more time to fully charge the phone.
Yes, Vivo S1 has dual 4G VoLTE support.
No. Vivo S1 does not have Qualcomm Snapdragon processor but it has latest the latest MediaTek P65 octa-core processor.
Yes, Vivo S1 has dual 4G support. You can use 2 4G network sim cards at the same time.