For using the activities overview quicky, there are a couple tricks you might like. First, to open an application without closing the overview, drag and drop it to a workspace instead of clicking it directly. Also, the shell has been designed to make searching really efficient, so as soon as you click the Activities button or hit the Super key, you can start typing! I can open gedit almost instantly, for example, by pressing Super, then "ge" and Enter.
You might like the dock extension for Gnome Shell. To install it, the people at WebUpd8 have a repository with a bunch of Gnome Shell extensions, including the dock.
To add their repository, open a terminal and type the following:
sudo add-apt-repository ppa:webupd8team/gnome3
sudo apt-get update
And then, to install the extension, type:
sudo apt-get install gnome-shell-extensions-dock
To enable the extension, first you need to restart Gnome Shell. To do that really quickly, press
r and press
Enter. Now open Gnome Tweak Tool (you may need to install that from Software Centre), head to the Shell Extensions section and turn on the Dock Extension! It will appear on the right side of the screen.
You can configure some basic settings for the dock in dconf. Open dconf-editor (again, you might need to install it) and, on the left, go to /org/gnome/shell/extensions/dock. From there you can choose the side of the screen the dock lives on, its size, and whether it autohides.