The light source is a special tungsten bulb with a mirror, something like the bulbs you find in ceiling lights. The light is diffuse and can be colored by turning the y, m or c knobs.
The film is held by the enlarger’s original film holder. I adjust as you can read here: How To Adjust for Low Distortion
Due to the construction of the enlarger head, the film does not get too warm. It does not bend or pop like you can sometimes see when slides are projected (half a century ago 
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