When you say "unique color", Windows just give the icons the same icons that the program has if you look in its Program Files. Firefox looks like Firefox, AIM looks like AIM (apparently yellow, I don't use it to know), Windows Explorer looks like a folder, command prompt is black, etc....whatever program is there, that is the icon used. Firefox just happens to be orange. Windows didn't assign it. That's just the color Firefox is.
If you want things to look the way they did back in Vista/XP (rectangular, instead of square icons), right-click your "Taskbar", then click "Properties". On the "Taskbar" tab, drop down the menu "Taskbar buttons". Change it to "Never combine". Apply > OK
Now things will look like they did way back when.
As for the background slideshow, did you happen to unplug from the power cord right before it stopped working? By default (unless you change it), Windows will not go to the next background while on battery power (to conserve energy). You can force it to change by editing your Power Plan's "Advanced Options" > Desktop Background settings > Slide show > make both settings ("On battery" and "Plugged in") "Available".
Did that solve/answer your problems? If not, just let me know, and I'll will be more than happy to help you out again.