Is it possible to adjust ISO, shutter speed, light intensity before and after rendering?
Yes. There are several ways. You can configure the camera optics and film properties and also the power of the emitters before you hit render. Then, while fry is rendering (or when it's finished rendering) you can fine-tune all these parameters with our tonemapping controls. These include the most basic ones (exposure control, gamma, etc...) and also a full Layer Blending control with which you can modify the powers, colors and temperatures of all the light sources in the scene selectively.
What are the ways of adjusting the final image directly in FRY?
As explained above, the Tonemapping and Layer Blending controls. Aside from color perception parameters (exposure, gamma, key, ...) some useful HDR RGB controls are present (temperature, R,G,B levels, histogram previsualization, contrast...).