Using F1 to choose your WM at the log in screen will show you WM
options that you do not yet have. It seems that the OS's standard
package manager, Meta Installer, does not bring in the entire WM.

In Fluxbox open the menu and go to; (Full
Fluxbox>Applications>System>Package Management>Synaptic) and you can
bring in LXDE and or FVWM Crystal from there.

Synaptic will not allow you to bring in Gnome or KDE. I do not know
why those are offered as WM options at the log in screen.

GQview is available as a photo viewer. It is much less of a pain in
the butt and uses less system resources than F-Spot or DigiKam.