Try zooming in (to get the fuzzy)... That's because it blurs them to stop them getting all pixelly. Furfags.
History and bookmarks disappearing? Very weird! The main visible feature of this version is the use of bookmarks/history/stars an' shi'... What a pain...
I only really use the tag things; facebook is my only bookmarks toolbar item, and it stays there nicely. I <3 tags; that's why I used to use delicious under ff2.
It's the little star that appears on the right hand side of your address bar.
It's not so much a "the difference is this" answer actually: A tag is something which you apply to a bookmark. So people say they're "tagging" a page, what they mean is they're creating a bookmark. You then assign the bookmark certain keywords, so that when you search those keywords, that bookmark will come up. (I've just done a mouseover on the star, it actually comes up with "bookmark this" - click on it again when you've bookmarked a page and a little box will come up letting you apply tags).
The point being that it's easier to search your bookmarks, and you can tag them with useful things, for instance, I've tagged "http://www.pcspecialist.co.uk" with "pc specialist", "laptop" and "computer" - so if I type any of those things into my address bar, that site will come up. Handy when you can't remember the name of the sites you bookmarked off the top of your head, only what they're about.