i'm not gonna lie i can say what i like about this but that would be bs ... I just like this work of your's because 1) it looks nice 2) looks like it took a lot of work 3) and its creative X) well those are my reasons X)
It is. Once it dries, you can paint and then you can rub it off of your paper. You don't need a special brush, just coat your watercolor brush with washing-up liquid COMPLETELY and dip it into the fluid. But buy good qulaity fluid (like Winsor and Newton), otherwise your paper will be damaged.