Regarding the camera angle, the only tutorial I know is this one.
You need to make the picture as a whole. The first tutorial link mentionned by Daulmakan should teach you how to set doors, wall and all kinds of obstacles on the picture.Cameras
Under Absolute World, you should see X, Y, and Z coordinates. Change the values in the X and Z boxes to 45, then close the box.
Thanks! That's all I needed to know.

Thanks again!