1.Nobody uses emerald (trust me you don't either).
2. Ubuntu already runs compiz from the start, just type ccsm in the terminal to configure it (if you have to, install the ccsm package if you don't have it)
3. I don't use application docks. However, there are two application docks that you would like, here's my opinion:
is my favorite, because it's the most featureful and can be made to look like OS X or any flavor you want... you get to decide.
awn (avant window navigator)
is a little less configurable, less featurefull but still looks nice. This is used a lot more, even though personally I don't like it.
4. I use shiki-colors gtk+ theme with the gnome-colors icon set with the shiki-flat window decoration... you choose the color which is what I like. I say it looks really nice, although it appears a little dark.
I don't run Ubuntu, but almost all Linux distributions share this in common. Good luck on your Linux adventure!