Hello and welcome to Ubuntu! there are a few UI designs, but im guessing you have the ever popular Gnome
For text :
Open a terminal and type
sudo apt-get install unity-tweak-tool gnome-tweak-tool
Once you have it under advanced settings, there is a "fonts section
To move applications to the desktop:
First off As a linux user, I recommend using the terminal and get used to not using the desktop! A better alternative is downloading Cairo-dock
If you must, and this goes against most linux users beliefs,
First copy your desired application's icon from the /usr/share/applications directory to Desktop,
sudo cp /usr/share/applications/filename.desktop ~/Desktop
Then change the permissions(give execute permission to the .desktop file) of copied .desktop file on the Desktop,
sudo chmod +x ~/Desktop/filename.desktop
Double click on the application icon to run it's corresponding application.
Power button:
Again most users use the terminal, and not buttons. Its traditional and faster. Learn these
sudo reboot (restart)
sudo shutdown -h now
sudo shutdown -P now
sudo poweroff (shutdown)
sudo halt -p
sudo init 0
I dont know if there is a way to change the top launcher, as that is part of the ubuntu file structure and cannot be changed.