Paul beat me to it… but yes if you want to do your photo compositing/editing back in Photoshop, you can apply elements on black and than comp using transfer modes in PS or Lightroom.
Note that on many of the Light effects, you can also set them to generate only the element over black (see image under Lens Flare parameters). This way you can test an effect on top of the image your applied, but switch it to over black before going back to PS. (You can even apply a black color layer (under color tab) and the flare above.
As far as using effects again on other images, you can save the Optics project as a setup under file OR you can rename and save your edited effect as a preset and make a collection of favorites.
Lastly - if you were not aware, the Lens Flare Designer gives the unlimited ability to refine your custom flares. You can add/remove and edit elements. It is quite deep but very useful. As an example here is a setup that I saved to download. I took a Flare preset, at top selected Edit Lens and removed some elements, added a few more.
Hope this helps.