-What exactly is a launcher?
Think of the launcher as your
"Desktop" on the phone. It dictates how your dock looks, how the app drawer looks, how many home screens you have, etc. The stock Galaxy S launcher from Samsung is called
TouchWiz, and is generally hated. It is slow, the app drawer isn't liked by many people because of the colored backgrounds it gives your apps, and doesn't offer much, if any, customization.
A new launcher, of which there are many, will give you many options to customize the phone to your liking
(I use LauncherPro Plus). You can change dock styles, hide apps in the app drawer, change the speed in which the app drawer opens, etc. You can have many different launchers at one time, so download a few and see which you like. Then you can use this app to switch between them until you find one you like....
https://market.android.com/details?id=ymst.android.homeswitcherfroyo
-How do you delete what you have searched for on Google?

Even after deleting all history, cache, cookies, etc. it still has what I searched for in google.
On your computer, sign in with your Google Account, and go here....
https://www.google.com/history/
From there you can clear your entire history, and pause it from saving as well.
Hope that helps. You didn't say earlier, which phone did you get?