Sinister means Evil... And more importantly for this, left.
Sinister works just like normal Good/evil homeworlds, except that everyone's goal is to eliminate the player to their left (while defending against the player to their right).
I think you use the same number of pyramids as a normal homeworlds game (5 of each, rather than the 3 of each size of each color used in binary homeworlds).
The pool will probably never be per player, as the scarcity of pyramids is one of the key components to homeworlds. Also, then you would have a larger maximum if you ever captured an opponent's piece.
I think that should answer your questions.
-Evan from chicago.