The second panel has options that you may wish to apply to the treatment:
Contrast + and Contrast ++: appear in all current V-Suite components. They offer an additional S-curve to boost contrast. You may choose none, one or both options.
Contrast - and Contrast --: appear in all current V-Suite components. Choosing one or both of these options will reduce image contrast to some degree.
Add Grain appears in several modules. It provide film grain simulation. It's best to test the impact of grain by choosing the selection preview option, so you see the effect at 100%.
Color Boost and Super-saturation are specific to Velvia Variations and is explained on the page for that script.
You may select any number of options to be included in the final treatment. But be careful not to choose conflicting options.

Keep existing layers: as its name suggests, this will keep any existing layers in your image and save the selected V-Suite treatment in its own layer. This is an opaque, merged layer that combines all existing layers. If you save the layers, then you will be able to fine-tune the effect of the treatment by adjusting layer opacity. If you have selected multiple treatments, the output from each treatment will be saved as a snapshot each with a layer named, for example, "Velvia Variations".