Any other must have "Saftey" addons for firefox?

WOT, Web of Trust

to keep your bookmarks "safe" use xmarks.
you could try using hidemyass when you feel the need
and annonymox for greater privacy, it gives you different IP addresses

when it comes to bookmarks and things of that catagory:

I use Roboform Everywhere.
Not free, but simply marvelous and the best of breed and most secure of that category of program. There are a couple of other programs. I recently attended a web security-related 2 day meeting and was surprised to find that roboform was recommended there.

Simply google Roboform, since to describe even the outstanding features is one big assignment.

you can have a free roboform addon for firefox,
xmarks just syncs your bookmark list to their server, which means you can logon to the xmarks site from any computer and have your bookmarks, on your pc's at home they can sync between each other so a bookmark you may make on the laptop will show on the desktop when you open your browser,
its not about bookmarks being hacked, a bookmark to a site is only the link to the site so no security issues there,
roboform saves your login information so you can click on a button and it logs you in without the need to type out usernames and passwords ,i too have used roboform for several years and it is excellent,
the free addon for firefox doesnt have all the features of the paid version but for the logon feature you cant go wrong,
i also sync my roboform data to my live mesh folder so it is backed up securely