Yes, Vivo V5s does have support for OTG.
Vivo V5s has ARM Mali T-860 MP2 graphic processor GPU.
Vivo V5s has Sony IMX376 Exmor RS sensor for the front selfie camera while rear camera is of CMOS BSI sensor.
Not at all. We have used Vivo V5s during our reviews and found that despite using for longer hours, we did not encounter any heating issues.