1. This program came with their default feature which are in their installation path; could be modified but is not so simple.
2. About dialog will show ONLY the imported plugins, furniture library and/or texture.

@techdoctor
If You see SOME texture and plugins in About dialog but no furniture library that's mean You've not import them; there is a lot on this site or on SourceForge.

@makeurmark
Of course it is but need some patience and work.
P.S.
I've spend 10 years with this great program and I don't discover (yet) all the features already provided by master Emmanuel and the community.
This forum is a real treasure for those who want to learn and use this program.

Anyway, keep asking. Someday You will be the one who offer answers to other new users.