Is there a way to save the program preferences (installed script files) before program exit? I have issues with DM1 crashing on exit, which wipes out user-installed scripts.
No, GMS 1 does not offer any way of saving the global preferences. Neither by script, nor manually. This is a GMS 2 feature. The command for it is
void ApplicationSavePreferences()
However, if you are interested in 'installed scripts' only, you can use script commands to install scripts into a *.gtk file and have that file in the plugin-folder. The file is saved on execution of the script (at once) and will be auto-loaded on start-up.
In a similar manner you could store the global tag-file as a separate .gtg file (and restore it later). But this will not save all your preferences, as some of them get written to the global tags on closing DM only.