The larger the number, as in. The smaller the opening the greater the depth of field. Depth of field refers to range of distance that the focus will be sharp. If the focus is sharp between 10 and 15 ' then the depth of field is 5' . Smaller aperature settings usually result in a greater depth of field.
Shutter speed is the amount of time that the aperture is open.
This is one way to control the amount of light reaching the film. TTL metering is electronically controling the flash with sensors built into the camera. This can control both timing and intensity of the strobe as well as the shutter speed. Film speed refers to the sensitivity to light for a certain film. A film speed of 400 will require less light to atain proper exposure than say film with a 100 asa rating.