Your first question:
Exiftool is usually available, so I did not add it to the package. If
missing, Fotoxx politely asks the user to install it. There are several
of these outboard dependencies that are usually present by default.
The appimage package on my web site was not made with your Recipe +
I did something simpler and easier for me to understand:
+ I used a program to list all libraries called by the executable
image, at all call depths
+ I removed those in your blacklist
+ The rest went into AppDir/usr/lib
The rest is standard.
This makes a 30 MB appimage that seems to run fine in the systems
tested: Ubuntu 16.04, 16.10, 17.04, Mint 18.1, Fedora 25.
Wayland and KDE need environment variables to work properly:
Likely the library list can be pruned since they are all available in
all distros, with some exceptions for version revisions. I have not done
Your 2nd question:
If Fotoxx detects that it is an appimage, the executable is relocated to
/home/user/.local/bin and the desktop file to /home/user/.local/share so
that system menu integration is automatic.