Rockwool is excellent.
125mmx75mm on the wood (what we yanks call 1x6s) to build the frames. Light weight woods work well as you really don't want them to weigh much. Bevel the outside front of the 12mm width when you build the frames so you don't get snags in the material. Of course, if space does not allow, you can use 50mm or 25mm. Bear in mind, the thicker the rockwool, the less you need to cover. If you use 75mm, you will just need to do primary reflections (2 spots on each side wall, 2 on the back, 2 on the ceiling). If you use 25mm (like I did to avoid infringing on your space, make a pattern that covers most of the walls.
If you buy bulk 25mm, you might save a bit of cash and you can triple them up in the 75mm frames or double them up in 50mm frames. Might be a better option. Build superchunks for floor to ceiling, and 75mm corners for wall/ceiling intersections. Go in steps. Do the corners first and see how it sounds. Add ceiling clouds and see how it sounds. Do the front wall (where you face) in the wall/ceiling juncture, see how it sounds. Do the back wall and see how it sounds. When you've got the room tamed, stop. Enough is enough.
AFA material, you're looking for a breathable fabric...go to the local sewing place and look for colored burlaps (not like burlap bags, but the cloth) or cloth recommended for speaker grills. You might be able to find these with pictures, but if you get white fabric you can take it to any silk-screening shop...don't use iron-ons (obviously).
Be sure to spray the front of the insulation with a coating to keep the strands from fraying through the fabric and getting into your room...They're not fun to breathe.
Figure out how you're going to mount before you start. If you are using Z-Clips (you can google that), make sure you get them all on in straight lines both on the wall and on the frames (you might have to put 5mm plywood across the backs to mount the Z-clips). I used picture mounting wire and fed the wire into the Z-clips to avoid putting backs on mine.
Did I cover all the bases?