I'd like to drop support for anything that uses the Amlogic 3.10 kernel as soon as we have a viable Amlogic mainline kernel that we can focus all of our development energies upon. That means dropping the Core which has a tiny userbase (so it's an easy decision) and the Play1 which has a load more users but an even older chipset.
Current indications are that we won't have an Amlogic mainline kernel for LE 9.0 (Kodi v18) so your Core box probably survives another release. No promises though.
The 8.2.0 release with have zero changes from 8.1.0 (and shortly 8.1.1) so you'd best read #6 again.
The OS configuration of LE on v8.2 will be the same as v9.0 - no plans to do major changes and the roster of binary add-ons we provide should be exactly the same. Kodi changes are unknown this far out, but as long as you don't go overboard with customised skins etc. things normally update okay. The kids box in our house has a deliberately "sensible" config and it's updated all the way from OE 3.0 to its current LE 8.2 config without any real-world issues. TL/DR; install 8.2 or experience a long wait 
Kodi Leia release content will be discussed at a DevCon event in Prague in mid-October. Part of that discussion will be when to start formal Alpha releases. LE has no plan to do it's own 9.0 Alpha releases until after Kodi starts shipping theirs and we can assess the state of them on the current range of hardware we support. Right now I'd guess things are 3-4 months from Alpha and 6-months from release.
Milhouse images for Generic/RPi are available for those who like to be on the bleeding edge of LE development. These images are fairly stable from a core OS perspective but there is still major plumbing to change on the Kodi side.
There are no obvious errors in the logs .. apart from one message which shows the box accepting an SSH connection/login.
Not possible. The config is hard-coded and (same as a hotspot function on a mobile phone) is not designed to be user-configurable.
Removing the add-ons lines from the Logfile before sharing isn't the same as removing the add-ons.
You might need to force the SMB client in Kodi (in Kodi settings) to use a maximum of SMB1 for compatibility with an older Samba version in the router. Kodi settings > services > smb client
<6>[ 307.216521@0] usb-storage 1-1.1:1.0: USB Mass Storage device detected
<6>[ 307.217677@0] usb-storage 1-1.1:1.0: Quirks match for vid 152d pid 2329: 8020^ random guess - make sure the USB quirks for the SATA adapter exist in our kernel
It appears some firmware went missing among the firmware repo cleanup's we've done. However, nobody has PR'd a change to re-add that firmware to the 8.2 and master branches on github yet, so the issue is not solved.
Find a USB "Y" cable that allows the HDD to draw power from 2x USB ports?
It will be under add-ons > programs in Confluence
Adding a Samba share via the "Add a network location..." browse option, including adding full credentials, should also work.
network browsing is dependent on use of SMB1 and there is no equivalent in the SMB2/3 protocol; blame Microsoft
You cannot "Network browse" to the box unless it has SMB1 active, but you can provide the full \\server\share path in the Kodi GUI and Kodi should connect to the share and prompt for username/password. I personally find it easiest to edit /storage/.kodi/userdata/sources.xml but Windows people tend to have irrational command line phobias.
Nope. Go into the services tab and enable BT first, then the BT devices screen will be active.
Running a torrent client is not a banned practice because bittorrent does have legitimate uses. However it's quite obvious from the log that you are using yours to steal the new Baywatch movie using a torrent file from TPB. This project does not endorse content theft/piracy and this is not one of the legitimate uses of bittorent we might entertain support for.
Not possible in Krypton. Might be possible in Kodi Leia if I continue to nag people on the Kodi side (as it's something I'd like to see too). No promises though as it requires core code changes (not just skin things) for it to happen.
