Actually, the HID setting still have a use in USBLoaderGX.
So, I'll try to answer your questions.
• Settings>Loader settings>Setting file : Create, Delete, no change.
Since r98 (loong time ago)
Nintendont can use two different method to auto-boot games : reading a file located on SD/USB which contains the path to the game to boot and the settings to use, or reading the configuration directly from memory.
If you choose to "create" the config file even if since r98 the loader is sending the settings by memory.
The advantage to create the config file (stored on root of SD or USB : nincfg.bin) is that it memorize the last used settings and the last launched game.
If the file is present,
nintendont will load it at launch if you launch
nintendont from HBC instead of USBLoaderGX. It will read the settings and see that you want to "autoboot last played game".
If you create the config, you can quickly launch last played game by launching nintendont directly from HBC without going to USBLoaderGX !
Create = it creates the config file (alowing quick launch from HBC->nintendont)
Delete = it always deletes any existing config files (preventing quick launch from HBC->nintendont)
Don't change = Doesn't replace or delete existing config file (Allowing default settings or game to be launched from HBC->nintendont but being able to play different games when launched from USBLoaderGX).
Best choice for newbie : Don't change. it won't create/delete/replace any file.
• Video deflicker: Remove anti-aliasing effect (blur effect) to make the picture more clear, but more edgy.
• Controller.zip is not downloaded from USBLoaderGX.
You need to do it manually, or from Nintendont menu (B -> Download -> controller)
• You can have per-game settings if you use USBLoaderGX, which nintendont doesn't provide.
• since Nintendont 3.304, HID setting is not used by Nintendont. The HID option is ALWAYS enabled by nintendont.
If you use a version older than 304, HID setting is needed !
if you use a version from 304 or newer, HID setting is ... depend what you want.
since r3.304, Nintendont has pre-defined internal controller.ini files (inside the boot.dol), but maybe you don't like the default button mapping.
In that case, if you have a controller.ini (or /controllers/ folder with the ini inside), nintendont WILL USE the controller files instead of the internal default mapping.
Enabling or disabling HID-USB Setting inside USBLoaderGX will not affect the fact that nintendont is now ALWAYS enabling it.
But USBLoaderGX is using that setting for other things : while you are still in USBloaderGX it's checking if you enabled HID.
If HID option is enabled, it checks if you have the controller.ini file present on the "Game partition".
If you have the controller.ini only on the boot.dol partition and try to launch a game located on a different partition, then USBLoaderGX will copy the controller.ini for you to the proper partition !
So, since r3.304, enabling HID is useful only if you want to use custom controller.ini to be sure it's correctly "propagated" to the partition where your game is located.
Keeping that setting Enabled if you already have the controller.ini on both SD and USB is not needed and will slow the game launching process.
It's better to keep it OFF when using r3.304+ but the option is still there to check and copy the file if needed by the user, AND if the user is using an old version of nintendont !
The loader allows setting different version of the loader per-game.
One game could use r3.319 and the other 3.304 etc.
HID setting is useful if you use older version.
Note: I will release USBLoaderGX r1244 which will stop telling the user that HID require controller.ini when detecting 3.304+
• Tuning HID-USB ON on (very) old version of nintendont will cause problem.
very old version used either HID or Gamecube controller.
Now it's multiplexing every possible controllers at the same time.
You can have Gamecube controller + HID USB controller + Bluetooth controller all at the same time.
Connecting a new controller will set it as player 2, player3 or player4 depending on already connected/powered controllers.
You might also want to set "MaxPAD" setting to 4 if you often play 4 players games.