Hello,
1. Probably applies to all ISOs. I had a crash and backtrace very
similar to this, which has been fixed:
https://github.com/calamares/calamares/issues/1061.
2. Pcmanfm-qt crashes with a missing symbol and probably needs to be
rebuilt.
3. Some parts of LXQt require xscreensaver but it's not installed.
(Suspend or hibernate tries to use it.)
4. Probably the installer should run with a window manager (which
doesn't run at least in the LXQt image, after choosing Install from GRUB
menu) as Calamares tries to open some windows, for example when a button
is clicked that opens a web browser (the one that opens Sabayon website).
I don't have access to that VM right now but hopefully this level of
detail is enough.