Your tank looks really nice. The water level can be kept right to the top as normal, I did this in my journal in my signature and had both riparium style plants and aquatic plants. I would keep your dosing pretty much the same if your still going to be injecting co2, also because any emmersed plants can sometimes have some very big hungry roots.
Ideal riparium plants or house plants you can use are big standard peace Lilly's, antherium Lily's, calathea plant, pothos which trails really well across the back of the tank....
Also any of the echinodorus species do do great grown emmersed with just the roots submerged.
It may be best to drop hydrophyte a pm as he could give you a list of many different plants to use.
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