Rooting the Captivate

[Delph]

I'm new to Android, and am interested in rooting my new Captivate, mostly to be able to download and install .apk files directly. So sorry if this sounds like a noob question. What does the phone look like after I root, specifically the wallpaper and my apps. Will everything look the same after I boot into root, or will it look different? What about the ability to upgrade to Froyo?