I am still not sure if I need to run Amethyst App thru Orbot app if I have Tor connected in Amethyst.
You can run Orbot in expert mode, it doesn't function as a VPN then, just a proxy server. Activate the Tor mode in Amethyst and it will use the proxy. You don't need to use the VPN feature of Orbot necessarily. This is how I use Tor in tandem with a standard VPN.