[Trac] newbie question - multi-project: tracd Vs. multiproject trac

[itsme213]

We want to use trac for multiple projects on our web host.

The two options I have seem to be:
- tracd: web host tells me I can start a tracd myself (ssh access)
- trac install: web host can setup a trac cgi for me.

(My web host cannot do the mod_python trac)

They also tell me that trac/cgi cannot do multiple projects.

Will http://projects.edgewall.com/trac/wiki/TracMultipleProjects work on a
shared-hosting setup (BSD, Apache-2)?

What are the pros and cons of tracd vs. the multi-project setup?

Where do I setup users authentication?

Where do I setup user permissions for each project?

Is the underlying trac functionality and web-interface identical?

Thanks!