a) Which file manager did you specify during the installation? Launch litestep\utilities\EvarConfig.exe to reconfigure it, or manually edit litestep\personal\evars.rc. It should point to explorer.exe or to another file manager of your choice, but not to iexplore.exe.

b) Those are themes that follow an outdated theme standard. Use the Theme Installer to install any new theme(s), don't extract them manually.