IOT2050 connects 4G by mPCIe modem details of script?

Now I can use mPCIe modem to connect internet by 3G/4G SIM card successfully (mPCIe is Huawei ME909s-120). Let me summarize what I've found first then I have some questions for better understanding the process of the script.

Basically, there're 2 ways to configure mPCIe modem.

1. The first method is from IOT2040 forum, How to use 3G mPCIe card for internet connection. This method you need some procedure to extract and install the file provided by the forum. Then, it'll ask to fill PIN, APN, user and password. Finally, we need to edit file “/etc/network/interfaces” and add “dns-nameservers 8.8.8.8” to connect internet by DNS name.
   
   
2. The second method is to use "iot2050setup" in PuTTy screen. Then in Networking -> Activate a connection we'll find 4G-cellular which we can activate and internet connection is available immediately. We also need to edit file named "cellular-4g" in folder “/etc/NetworkManager/system-connections/” and change "autoconnect" from false to true, to make internet connection is available after rebooting.

Question1: What's the script inside method 2 so that we don't need to fill PIN, APN, user & password? But we still can connect internet successfully.

Question2: with the first method, the channel you get when checking with ifconfig is "ppp0" channel. While in method 2, you'll get the channel named "wwan0". What's the command to choose this channel?

Question3: I notice that once I setup with method 2. I cannot use the same modem with method 1 anymore, even I restore original image to SD card. I believe some script command of method 2 should setup something in modem. May I know how to bring it back to ppp0 again?