I only have shrimp in mine as it's not as big as the one you're planning and 2/3 of the footprint is land. If you look at the thread in my signature you can see some of the build plus my other one which is similar but open fronted.
I can highly recommend Dendroboard forum for information regarding the top part and how to build the backgrounds. There are various ways, the one in the photo I posted is cork bark siliconed to the glass with sphagnum moss in the gaps and the other one in my thread is built the same way as the one in your image - with expanding foam, silicone, bark and coir. The misting is automated with a MistKing misting system and ventilation with some small computer fans to prevent the air becoming stale and keep the glass from fogging up. Dendroboard focuses on keeping dart frog species and all the builds are therefore fish safe too. Many of the members are also very knowledgeable on the plants which will do well.
If I'd built mine to house fish in the lower part, the aquarium part would be the equivalent of 60cmX45cmX20cm, so around 55 litres.