default apps

[Matthew Monaco]

I'm finding inconsistent information about how to set system-wide default 
applications.

Do I do it with mimeapps.list or defaults.list?

In general is the default app part of the desktop spec or the mime spec?

Is there a difference between doing it systemwide vs per-user (filenames, 
locations, etc)?

I'm using GNOME 3, are there are special quirks here I should know about?

Unlikely, but does anyway know of a way for firefox/thunderbird to honor the 
system settings for mime types? This in particular has been very frustrating for 
my parents, it seems like every day these settings change.