What do all the little icon things on photoshop cs4 stand for?

Like on the side theres a band-aid, a paint brush, a water drop….
But what do they all mean.
And i mean ALL of them, not just the ones i mentioned.

i know what the regular paintbrush means, and the one you use to pick up a color thing.
Please and thank you! [:
The hover thing isnt working.
(i think its cuz mines like free bottleg version type of thing. haha)

i think thats why the f1 thing isnt working either.

Photoshop Elements – Does it stand alone? Genereal Photoeding ?’s?

A question I have is can I use Photoshop elements 7 as a stand alone program or do I have to actually have Photoshop CS or something like that. Is Elements an add on type of thing or can I use it by it’s self? Another thing-I I hear gimp is a good program but I was wondering does the free version have a brushes option( I know I’d have to dowload them if so.)