<sarcasm>No sir, I wasn't being sarcastic at all. I actually think it would be awesome to play Tokyo Mirage Session #FE on 13,889 floppy disks.</sarcasm>
The usefulness of an installable Loadiine for people that use it is not lost on me. Until there is an installable version just do the same thing you would for any homebrew you want on the Wii U menu. Use Haxchi or install the channel version of HBL and launch from there. The OP was talking about more than just an installable version. He was also talking about active development of Loadiine. Most of what he was wishing for doesn't even make sense in regards to Loadiine. From what I gather online ain't never gonna happen with Loadiine. Loadiine "tricks" the Wii U into thinking it's a title with SD card access (Mii Maker or SSB). Online doesn't work because the Wii U thinks it's running a different title than it actually is. A USB loader would be awesome but that's a homebrew onto itself. Loadiine works using the above mentioned SD card exploit. It would make more sense to integrate SD card loading into a new loader, not to integrate USB loading into Loadiine (assuming that it's possible).
1. Installing games using the Brazilian method involves so much less bullshit it's not even funny. Firstly you can just download them from NUS. No fucking around with ad link sites, joining random forums and sorting through posts to find games, slow download speeds, or waiting because you reached the daily download limit, etc. Downloading from NUS I've seen my entire bandwidth saturated. Downloads have been as fast as 15 MB/s (120 mbps). I suppose you can convert a game downloaded from NUS to Loadiine installable but that's another thing to screw with. Secondly the installation process is easy. I'd argue it's even easier than unzipping the files to the appropriate place for a loadiine install. No fucking around with multiple part zip files, deleting them afterwords, unzipping the update/DLC to a separate folder and pointing Loadiine to it. Installing games to USB using a program like Wii U USB Helper is easy by comparison; browse available games complete with screenshots and game information, select the games you want to download, download them in batch (with updates and DLC at a speed that will saturate most peoples connection), copy them to the SD by selecting the games you want to add to the copy queue and copy them in batch, use WUPinstaller Y Mod to install all the games in batch. No fucking around with file management except for deleting the install folders off your SD card when done.
2. Maybe, I dunno.
@xtheman166 seemed to indicate that it's not difficult to repack a Loadiine installable modded game into a USB installable game. Even if it is way easier on Loadiine there's like two games you'd probably do that with. Tokyo Mirage Sessions and Xenoblade Chronicles X. If I were interested in said mods I'd be willing to put in extra effort to play the USB version.
3. To be honest I'm not familiar with VC injects. I assume it's taking a ROM which is not available as a VC title and overwriting an actual VC title. If that's what VC injects are then who the fuck cares if it's easier in Loadiine? That's the most bass ackwards way to play a ROM I've heard of. I've got like a dozen devices that would be better for running ROMs. Just use an old laptop or a Raspberry Pi. Alternatively you could wait for the Wii U emulators to become more mature. Apologies if I'm totally wrong on what VC injects are.
4. What for VC titles? Again being able to use any controller you want for an emulator is standard. If you're talking about Wii U titles then cool I guess. The gamepad has added functionality for most games and the Pro controller works awesome so I'm good. Besides, I'm pretty sure that there's a homebrew that would allow this functionality. HID to gamepad I believe.
TL;DR The Brazilian method is an objectively superior way to install and play backups. Nothing wrong with continuing to use Loadiine, but it should not receive any significant development resources. It's a dead end.
just use FTP and replace the modded files. Or, you can just decrypt the files, apply the patch and repack everything into an installable wup package. Consireding the limitations of SD access speed... I don't think FAT32 is worth using Loadiine for.
