I can't answer the question of whether you should use Nautilus… you might want to ask on the Nautilus mailing list or IRC channel (#nautilus on irc.gnome.org).
Documentation for GObject Introspection is a work in progress, but you can use g-ir-doc-tool
to generate Mallard files, then use yelp
to view them (or yelp-build
to turn them into HTML). There is some documentation of the process at https://live.gnome.org/GObjectIntrospection/Doctools