Most "builds" are a mix of legitimate and piracy add-ons. As a broad sweeping but fairly accurate rule, if a repo or addon is advertising "free movies" or "free sports" and the source is not a national free-to-air broadcaster in the country you reside in, it's piracy.
See: Official:Forum rules/Banned add-ons - Official Kodi Wiki
It's theoretically possible (if you do the development) but it uses an Allwinner SOC so you may have to contend with patchy Linux and u-boot support as they are known for providing incomplete sources in violation of various GPL licenses. It wouldn't be our recommendation.
LibreELEC provides no support for users who install "builds" like Spartan that encourage piracy. I've pinged Kodi folks to add it to their list of banned add-ons. Thanks for bringing it to our attention! 
LE v7.90.001/002 use the KMS video driver which behaves badly on older Intel GPUs. In v7.90.003 (out shortly) and current Milhouse builds we reverted back to the Intel driver which should solve issues like this.
If you want fast file-copy speeds you'll need to format as ext4 (kernel driver) from within LE or anothe Linux install, but ext4 is not be readable on Mac or Windows. If you want cross-platform support use exFAT, which will be slower for file-copy (as it uses a FUSE userspace driver) but can be connected and read on any OS.
The Tvheadend add-on is not embedded in the OS, so it makes no difference whether you are using Milhouse/CvH or official builds.
I just saw in one of the forums that LE has known problem with PCM audio?
ODROID Forum • View topic - LibreELEC 7.0.2 - Kodi Jarvis 16.1 - Archived - LE Tips HERE
If you are using Odroid C2 hardware this is relevant. If you are not (and we don't know because you've not told us much) it not irrelevant.
The challenge with Jarvis is that Kodi team are not accepting patches/changes; they already moved all development to Krypton. If you can point us to a patch that can be added to a future (v7.0.3) release we can test it and have no problem including it.
It may be possible to copy the binary from an Ubuntu instance that shares the same kernel arch (e.g. x86_64, arm). If that doesn't work, someone needs to create a build-system package for htop and submit it for inclusion with the "System Tools" add-on bundle on GitHub.
It's relatively simple to change the skin that's embedded in the imag but add-ons require build-system packages to be created to pre-install them. Both tasks will require you to understand our build-system (which has no manual or instructions). IMHO it is easier to set-up one box, take a backup, restore the backup to the other boxes. This also preserves the ability of skins and add-ons to update themselves when there are new versions available. If you embed the add-on into the read-only SYSTEM image this capability is lost.
Go into LE settings and set a "wait for network delay" of 5-10 seconds. Many low-power arm devices have slow(er) loading network drivers and because the OS boots fast Kodi can be started before the network has finished initialising, so Kodi cannot connect to the SQL database. Adding a delay allows the network to come up first, and then things work.
Go into LE settings and enable "disable password auth" in the SSH section.
DaVu: This would be a great topic for another HOWTO video
All you need to do is change the PKG_URL value and githash for PKG_VERSION in the add-on package.mk to pull from your own clone of the Tvheadend repo. If you are intending to fiddle with things long-term you should always be working in your own clone of a repo as this gives you control over the changes you fetch/merge into your local branches. If you blindly trust whatever we (or Tvheadend) people do upstream with a direct clone of our repo and "git pull" we'll eventually do something that wrecks your local changes
which is also more secure than using a password
You need to create a "patches" subfolder in the package folder, then add "diff -Naur" patches to that folder in <package_name>-<package_version>-001-name-of-change.patch format. The numbering decides the order that patches are applied. The default package sources will be unpacked and your patch-set of changes will be applied before the package is built. Have a look at other packages; there is no manual for the LE build-system but it is full of prior art 
Enable "Advanced" or "Expert" mode in Kodi settings, then you have the option for passthrough. In basic mode this is hidden.
