[Android Q&A, Help & Troubleshooting] Vulturon:
Sir you helped me alot, no problem I pressed the thanks button! But can I continue asking? Won't be too much I guess, hope I didn't bother your time...

1. That means I have to use LG Flash tool to flash stock 5.0 firmware (.kdz)? Which is 'V21a-HKG-XX'. But stock firmware 6.0 (V30c-HKG-XX) had released too. What exactly should I do beforehand...? Because before you said I am good to go but there seems to be something missing...... I am not challenging you sir, I just want to be sure and not missing any important steps so that my phone turns dead... (for sure information I wish to flash resurrection remix latest official 7.0 Nougat firmware)

2. So if what said in (1) is true, I need to flash stock 5.0 or 6.0 kdz first to turn the phone into clean stock 5.0/6.0, root it , then use Flashify to backup stock kernel/recovery (these are 2 things? I thought that was the same thing...), correct?

3. I found twrp recovery here: https://twrp.me/devices/lgg3europe.html by typing 'device' on the upper right, then type D855, all it appeared is only "TWRP for LG G3 Europe"... Plus, I notice in ROOT G3.com that twrp had different version for Android 5.0 and 6.0... So I am confused again, because if the above link is official website for twrp, it didn;t state that lollipop(5.0) and kitkat(4.4) has different twrp...

4. Derived from (3), as I am not sure which twrp .zip file should I download, I saw on official twrp web that it recommends "official twrp app" to install the recovery, I think it can detect my device and find the only appropriate one for me? I saw quite some people flash it using Flashify app, but I just want to know more and make it clear...

5. https://xdaforums.com/lg-g3/development/rom-t3543815 <- In this page, I found

"ROM OS Version: 7.x Nougat

ROM Kernel: Linux 3.4.x

ROM Firmware Required: 4.4.2/6.0 + TWRP

Based On: LineageOS"

On below. Is that mean 4.4.2 or 6.0 as the current system android version is also okay for flashing it?

6. In this page, which is another RR rom "stating" it is official: https://xdaforums.com/lg-g3/development/rom-t3507493, said that:

GApps - opengapps.org (ARM-7.1-PICO)

On below. Firstly, can I download Gapps on here: http://opengapps.org/?

If possible, than shall I choose like what it said, ARM, then 7.1, then PICO ( yes I think I only need minimum package)? Because I am not sure I should use 7.0 or 7.1, and ARM or ARM64...

7. Seems there are quite many version of RR, I googled "resurrection remix' go to their offical page, redirected me to sourceforge, https://sourceforge.net/projects/resurrectionremix/files/d855/Official/ I think I will download the latest date "20170110" version. If I am not wrong this should be the official not nightlies build (you will notice there are nightlies).

Refer back to (6), which type of Gapps should I use... AMR64, ARM, 7.0? 7.1?

8. So wiping 'system, data, cache, dalvik cache' these 4 things will really erase all things and get clean enough?

Also, https://xdaforums.com/lg-g3/development/rom-t3543815 here, below:

-INSTALLATION INSTRUCTIONS-

- Download the latest build

- Download Gapps (ARM 7.1 Pico/Nano/Other)

- Take a nandroid backup

- Recommended - Full wipe and factory reset

- Flash ROM using latest TWRP 3.x Recovery

- Flash Gapps

- Reboot.

- Enjoy!

They recommend press factory reset... Should I do the same? Is it better to press because if the 4 wipe 'system, data, cache, dalvik cache' is clean enough then reset is not needed...

--------------------------------

Opps....... Really sorry sir... When reading your reply one by one that much question appeared again... Really sorry, hope you don't find me annoying... SInce you are the only one reponded and you are experienced, so I wish to grap the chance to learn about it... Thanks a ton. You can have as many thanks button pressed if you want, I have no problem!