A: Only if the bootloader allows it. Many devices block downgrades to prevent security rollbacks.
One trap to avoid: The official Tenda website does publish separate firmware for each FCC ID. Instead, it publishes firmware packages for each hardware revision : F3 v2.0, F3 v3.0, F3 v4.0, etc.. If you attempt to download firmware for F3 v4.0 and install it on a V7TF3-16 router, the upgrade will fail (and may damage the device).
Upload the downloaded V7TF3-16 firmware file directly from your local machine.
Access the latest firmware packages for the F3 router at the official Tenda Global Download Center .