Diffusion in a small studio??

Hello everybody! It`s my first post in this forum, but i`ve been reading for a while... I`m from Hamburg, Germany. At the moment me and my partner are planning our new studio which we are going to build the next months. But before that I`ll problably have some questions regarding several problematic issues.... Our rooms gonna be very small, something around 13ft x 11ft x 7,2ft (low ceiling, basement). Control room and "live" room (recording) will be similar sized with different acoustic treatments. Now one of our basic ideas is to work with lots of diffusion in the live room to make it sound bigger and more balanced. Because one of our goals is to have "quite nice" sounding room, especially for recording strings for example. Is it possible to "go the other way", that means using absorbers (mainly bass traps) AND diffusers in such a small room instead of solely absorbing everything in order to get a room sounding quite dead? Same idea for the control room. We wanted to create a kind of "live end" behind us, using diffusors? Special question: On many pics of high end studios (for example the ones from RPG, http://www.rpginc.com ) you can see them using ONLY diffusors that work horizontally, why? Isn`t the vertical diffusion just as important? (Especially with a low ceiling as ours??) Do you guys know a method of building own diffusors (on the basis of the Schroeder Diffusor), or does it make sense to buy commercial ones (RPG e.g.) and spend your precious time on building the rest of the studio ;-) ?? Thank you very much for your help! Greetings, Schroeder