It looks okay to me, but then I don’t use a local server (but I have done lots of port forwarding in the past).
Not really. You’d need a way of forwarding the data relevant to your local server and i doubt that you can do that on your phone. Some mobile providers will be blocking the relevant ports anyway, so even if you had a 3/4G router it nay not work, see this:
Double NAT seems quite common in some countries, especially in Asia. More on it here: