2. You can buy thinly sliced beef at Japanese/Asian grocery stores. If you cannot find it, you can make slices yourself. Please read my post Beef Rolls with Asparagus.
You can substitute beef with thinly sliced pork if you cannot eat beef.
3. Shirataki is made from konnyaku potato flour. Its texture is like very firm jelly. It comes in a clear bag filled with water. You can buy shirataki at Japanese/Asian grocery stores.
4. Common names of shungiku in English include garland chrysanthemum and chrysanthemum greens.
Some vegetable shops sell shungiku, often at Asian grocery stores but I find that in Sydney, it is rather seasonal (winter-spring vegetables). So I often use spinach as a substitute when I cannot find shungiku.
5. The proper way of cooking sukiyaki is to use a piece of beef fat to oil the pan. You only need about 4cm x 4cm (1½” x 1½”). If you can obtain beef fat, I strongly recommend that you use it. It will give the sukiyaki much better taste.