No. Vivo S1 does not have Qualcomm Snapdragon processor but it has latest the latest MediaTek P65 octa-core processor.
No. Vivo S1 does not have the front camera flash. It has a display-screen flash.
No. Vivo S1 does not have a hybrid sim slot. The mobile has a dedicated MicroSD card slot. You can use a memory card of up to 256GB.
Yes, Vivo S1 comes with 18W fast charger in the box and the mobile has fast charging support.