Yes, Vivo V11 Pro does have the OTG support.
Vivo V11 Pro is very much eligible for the software update. The phone comes with Android 8.1 out-of-the-box. However, Vivo has not yet announced the further upgrade of the software.
Yes, you can purchase Vivo V11 Pro via without credit card option. Check out this video - this will help you to understand the whole process.
Yes, Vivo V11 Pro does have the in-display fingerprint scanner.
The Vivo V11 Pro is a solid all-rounder at Rs. 25,990 and offers better value than the Oppo F9 Pro (Review), but for a bit more money. Think of it as a Vivo X21 with a bigger battery and better front camera, but at a much more reasonable price, which is a good recipe.