The lily pads just go the surface and stop, and you can clip the shoots anytime. As for cutting tall crypts, I suppose you could, since it would be like cutting the tops of vals — but they grow pretty slowly and light levels will effect how tall they get, so you might not need to clip them.
Vals would definitely be a great choice for adding height to an aquarium. They are easy to maintain and will grow quickly to the top. There are countless easy stems in the rotala, bacopa, and ludwigia families that will grow tall and thrive under those conditions. I would also recommend placing some moss on your driftwood, as the shrimp will really enjoy picking through the moss.