Hi, the easiest way to connect a camera is to use an Rpi camera plugged into the camera connector on the Rpi. I believe you can also connect a webcam to one of the usb ports on the Rpi but you loose some resolution. As far as streaming goes you'll need advice from those who have done it - I haven't had any experience with it. Good luck.
There must be an easier way!!!!!
I hope there is.....I haven't found it yet.