I am glad you are back on track.

If you are just playing around for now - with the concrete bonder you can adhere the final putty coat to nearly any stable (meaning non-flexing) but rough surface. Even if it cracks slightly, it still shouldn't break away. There is a limit of course. You will have to find your own limits - the norm is to avoid cracking. Drywall, however, cannot take the weight of the putty. That 'handibacker' concrete panel board 1/2", anchored to the wood wall studs, then expanded 1/4 mesh - then your three coats - that should be sweet enough. This is still removable too.

I also forgot to mention that the first coat contains cement more than lime.

One thing I like about fresco is that you can paint out of doors. After it rains, the fresco shines in its brilliant colours and with the fresh greens of the garden - splendiferous. Don't leave it out over the winter though. This is type of painting which will attract people to true fresco I think. Even if you leave them out, and repaint new frescos every few years - thats fun too (and good for business).

The biggest problem of fresco is weight. There is a special hand truck which can handle (meaning lift 8 foot in the air onto a wall) up to 150 lb slabs. You could use it like an easel. This is called a drywall handtruck - and you can usually rent them before buying. A 150 lb slab would be 15 sq foot if you are careful with your materials. I am working on new lighter slabs now though - we will see. The other option is to beef up the handtruck, possibly with some bigger, inflatable wheels (so it can travel rougher ground) - add the electric engine, and laser guidance system - wait - i'm getting carried away now!