a) The OP used our USB-SD Creator app which creatse a USB directly from the img.gz file - so there's absolutely no need for unzipping to get images and using Win32DiskImager or other tools.
b) You only wipe the HDD if you select the HDD as the install target. If you insert a formatted USB it can be selected and you preserve existing HDD content - which is what the OP was attempting.
OE can be updated by dropping LibreELEC-Generic.x86_64-7.0.2.tar into the /storage/.update folder, see:
Good luck remaining with OE .. you'll need it.
Wow, is available now. Well don job to OE Team!
Freudian slip? .. I suppose "former OE Team" sort-of applies to most of us, but we prefer LE 
To change the Intel driver you only need to change the githash in packages/x11/driver/xf86-video-intel/package.mk and it will download/use the driver at the appropriate commit; although Intel's development repo is further upstream than the freedesktop.org one we use. You should be able to change the repo URL used to point it at another one. The same general process can be applied to most other packages. The build system is fairly simple (e.g. logical) once you figure out the general build workflow.
NB: Some of the devs (and/or people with solid building experience) hang out in the #libreelec IRC channel on freenode. It'd be easier to chat there than give major instruction via forum posts.
Our daily increase in active-install figures prove the Generic image is good and it makes no difference whether the USB is created on macOS or Windows as you're writing the same image to the USB stick. However, older NUCs can be finicky with USB booting (avoid using USB 3.0 ports) so you may need to fiddle with boot options in the BIOS and/or maybe update the BIOS to resolve Intel firmware bugs first. People definitely do use NUC's; they're a popular platform among our users.
Aeon Nox is available from the official Kodi repo, so there's no need for custom repo locations unless you want to be on the bleeding edge of untested Kodi development (in which case black screens and bugs are self-inflcited and not our concern). Go add it from the official source.
Our website needs updating to remove references to gaming in Krypton as development has been slow and the feature(s) needed didn't make the cut for Kodi v17 .. they will carry forwards and hopefully/maybe arrive in v18. That said, there are some community created builds that bundle retroplayer or retroarch components in to make setup of things easier - have a look for @escalade's "enhanced" builds and read his release thread for instructions on where to obtain other bits. NB: If you're using RPi3 you could also swap SD cards and use Lakka directly. LE v8.0 is a way off yet 
Ubuntu will be more flexible for installing random apps, but flexibility also brings complexity for you to manage. LibreELEC is less flexible (a limited range of apps available from our add-on repo) but hard to break (most of the filesystem is read-only) and easier to update. If you don't have much experience with Linux, LibreELEC should be easier for you. Kodi should be functionally the same in either distro.
NB: You can install LE to a USB key (boot from the installer USB, install to a second USB) for testing.
This is normal. If you migrate from OE your existing config.txt is not touched to ensure any customisations you made (e.g. overlays) are retained. If you clean install LE the config.txt file will only have references to LE.
I didn't look at the logs, but Kodi folks have been playing about with inputstream API things (or forgetting them) and that's probably the cause. Now that Kodi moved to beta the PVR/DVB front-end apps should start to stabilise. Please check again with v7.90.005 when it's released (it's work in progress) as most Kodi sourced add-ons will be bumped to match at the same time.
Skins are installed from the Kodi repo, so the Studio Icons aspect is not a LibreELEC specific issue. The profiles issue should be tested on a current alpha build and if the same issue exists in Krypton it can be reported to Kodi devs via the Kodi forums. You can report it for Jarvis too, but since all Kodi activity moved to Krypton months ago nothing will happen.
There is no official LE 7.1 build for the C2 so you'd need to ask that question to whoever is taking liberties with our version numbers and creating that community build.
tester100: Let us know when you finish reverse engineering the pre-compiled Android binary code and have something to share that we can compile to use in LE. Thx
There's a couple of extended-staff with WP boxes who have tried (and failed) to replicate the issue; they are able to install things okay .. so honestly I have no idea what the problem is 
After trying Tranmissions (it works funny sometimes, changing the download directories and has few settings), rtorrent+rutorrent (some rutorrent addon destroyed all my seeding torrents, plus rutorrent is not working in LibreELEC so it seems it has no maintenance); I tried Deluge and I loved it.Can it be installed on LibreELEC as it can be, for example, on Raspbian?
It's not possible to install it directly (as above) and we have no plans to add torrent client apps to our add-on repo (we're a media distro and these apps are used to steal media) but if you're using Generic/RPi/imx6 we support docker and someone has probably created a docker container for the app.
The better way to do it is a systemd .mount file in /storage/.config/system.d (look at the sample) but the same autostart.sh method will continue to work without issues.
run "dmesg | paste" and share the URL
master according to the build dirs (wrong kernel for 7.0) but make sure it's a full clean build and clear ccache
