The idea of this project was to make possible all of that spaces that you asked. I haven't done too much changes from the initial structure and the initial spaces. Seeing that the apartment has a considerable elevation, i tried to use it, adding a space for a studio and a second bedroom.
I used the central space of the apartment that it has the higher elevation to create this half floor and becouse at the ground floor i put spaces that has seconary funtions. Having windows with height 2.75 cm, the spaces at the half floor have natyral light too. The living room and the matrimonial bedroom have the initial height.
The half floor can be realised with lightweight metal structure.
I made some renders to create you an idea of the space that i create with the half floor. I used light and neutral colors becouse to look a biggest space.
Hope you will enjoy it.