2. Chunks + optional multithreading.
3. The UI is fairly extensive and customizable. You drag skills to occupy some 40-odd HUD buttons. Most buttons are also associated with hotkeys on the keyboard (e.g. 1-9 for this row, shift+1-9 for this row.) Players might have 20 or so spells or abilities, but learn that it's typically most effective to adapt to using the 2 or 3 most recently awarded by earning class levels.
3. The UI is fairly extensive and customizable. You drag skills to occupy some 40-odd HUD buttons. Most buttons are also associated with hotkeys on the keyboard (e.g. 1-9 for this row, shift+1-9 for this row.) Players might have 20 or so spells or abilities, but learn that it's typically most effective to adapt to using the 2 or 3 most recently awarded by earning class levels.