Generally you can still use the same method as described. Unfortunately each helicopter has little bit different mechanics. Some helicopter manuals are recommending how to set the tail mechanics so you can proceed according them.
But in any case the servo arm should be centered when you enter the Servo tab/Subtrim (tuning) menu.
The instruction in the manual is mainly because it is easier for beginners to set 0° everywhere. But advanced pilots can use their knowledge to possibly improve the performance little bit.
You can fly with the Wifi-Link powered if you enable Auto-Turn Off feature. You can do so in the Web Interface at the home page. (usually at
http://192.168.4.1)
It will then turn off Wifi-Link if nothing is connected - the Status LED will be Off. So then it is like nothing is running.