The OS used int htis project is Raspbian, because I'm a more familliar with debian and it already supports python and makes the GPIOs easily accessible.
Download it and flash it on a SD card with 4GB or more. Plug it into your Pi and add the USB WiFi dongle and the camera. Also connect it to the internet via the ethernet port.
You can decide to configure it via ssh or the keyboard. To configure it via ssh you need the IP-address. Some router web interfaces allow you to see the IPs of all devices in the network.
At first boot up we login with the user: pi and password: raspberry and run
In the menu we first expand the file system, change the user password (password of "pi"), apply regional specification if needed, enable the camera. I also overclocked the Pi to 950 MHz. In the advanced options you might want to change the hostname of your Pi and split the memory to 256MB for the GPU. Finish the configurations and reboot.
After that we run
sudo apt-get update
sudo apt-get upgrade
Now we want to install the wireless network manger wicd.
sudo apt-get install wicd wicd-curses
When that's complete we can run wicd and setup a wireless network connection.
Whe that's done you can software-shutdown the Pi, remove the ethernet cable and boot it again. Now you should be able to ssh access the Pi via WiFi.