SummerBoard for 1.1.1 scrolls left and right, just like springpatch. Customize is all you need to re-arrange your icons, the part about the smbprefs (SummerBoard preferences) is just so all your third-party icons are hidden onto the second screen like you were asking about.
No, it also adds homescreen wallpaper (and i think this is the only way to get that). It has theme support (Icons and such), and yes some preferences that effect various things on your phone as well