1) The General's power is Mandatory but the text says "he may draw" cards. How does that work? Seems like the power is Optional.
The General must use its power. This means the General must have the option of drawing cards and the General's allies must have the option of drawing cards. If the General's power were Optional, the General could deny its allies the chance to draw cards.
2) What does the "afterwards" mean? After the encounter? Only after the General draws cards? What if the General draws no cards, can the allies still draw?
To me, the most straightforward reading is that the allies each get a chance to draw after the General decides whether or not to draw. I see no reason to infer a delay of several phases between the General and its allies drawing, nor do I see any reason to infer that the allies' chance to draw vanishes if the General chooses not to draw.