It looks gorgeous, but you could probably save a great deal of money by purchasing or adapting a nice looking desk and a well-designed table easel. I also seem to remember there was some sort of easel contraption that clamped to a desk.
But if your studio is in your living area, as mine is, then the extra expense to keep the area looking presentable might be well worth it.
Is that a glass palette in the desk? I don't see how one would be able to access the drawer's contents while the palette was in use, but with some tweaking, it could work and might be quite handy if located in just the right spot.
Although they're mostly used for plein air painting outside, you might consider looking through the websites of the companies that build pochade boxes for other ideas. Companies such as Guerilla Painter have been building pochades for years and have come up wth some very clever design approaches and accessories that might be nice to use for your set up, and/or might spark new ideas for it.
Lucky you to have a friend to build you what you need...