Yes! You can for example use two distortion nodes in a row for a more distinct distortion effect, or use 3 of them in parallel with 3 images to create a fringe/chromatic aberration effect.

The only limit is your imagination.

No. That's the main idea behind the modular concept.

Only add the nodes you need.

Definitely! The demo video and some renderings were created with EEVEE. Just make sure to have at least 8 samples for acceptable results

Yes, but you will need to make small adjustments to the node. All you need to do is to take the alpha channel and use it to control a mix shader with transparency connected to the first socked and my shader connected to the second one.

This setup is done with the full (default) setup, with chromatic aberration, that's why it needs the 3 duplicates of the textures on the bottom left, therefore you should mix the alpha channels of the 3 image texture nodes with the values above. If you don't want to use chromatic aberration I recommend deleting the nodes to make it render faster, the node setup becomes much more simple. 

This also works with the Lite version