The issue is that I don't know how many GB it still really needs (even if I saw the value of 160GB globally on some sites)
I had
120GB free few weeks ago on my "Windows C:" disk
with Armory already uptodate and now I have only 4Go on this disk ...
My %APPDATA%/Roaming/Bitcoin directory is currently around 117GB
I'm going to move it on a new disk. How can I do it properly without restarting from scratch, knowing that Bitcoin core node is currently updating ?
The reason why there is no "mempool.dat" in your Bitcoin folder is because your Bitcoin Core version is outdated. Updating it will certainly boost the time required to fully sync. So the first things should be updating both, Bitcoin Core to 0.14.2 and Armory to version 0.96.2.
If your node has problems with connecting to others (you can check it in the debug window), then I recommend to exit core and delete "peers.dat" in your datadir and start it again.
Regarding your capacity issues. If you have an external storage I would recommend to just close Armory or Core and copy your datadir in "%APPDATA%/Bitcoin" completely to your new external HDD. Then go to "%PROGRAMFILES%/Bitcoin" and drag-and-drop "bitcoin-qt.exe" with your right mouse button to your desktop and select "create shortcut". Then right-click on your new shortcut and open properties. In the target line attend at the end of the line " -datadir="F:/YourPath/"". In your path enter the location of your copied blockchain files on your external HDD.
The next step is to open "Armory (Offline)" and go to settings. In the field bitcoin home dir you also have to specify your new datadir path.
When you have done the above start with your desktop shortcut bitcoin core and try if it works. When it does you can delete your old blockchain files on C: and let core fully sync.
- Why do I need to update so many blocks (weeks), as my Armory wallet 0.96.2 was already updated ?
In later versions of Armory the green connected label doesn't mean your node is fully synced. It just indicates if Armory is connected to your Bitcoin Core Node, which is running in the background. You can check how much percentages your node is behind by opening "%APPDATA%/Bitcoin/debug.log" and open it in your note pad. Scroll to the buttom and check the lines of "UpdateTip" for the percentage.
- Will Armory wallet update again for hours after Bitcoin core node blocks update ?
It depends on how many blocks your node is behind. But I recommend running Bitcoin Core only instead, until it has fully synced. Afterwards you can exit it and run Armory again.