1. Lost Souls are put in play whenever they would be moved from deck into a hand - usually draw, occasionally search or take. You only draw a replacement when the LS is drawn. Og is a "look and take", which is not a draw, so the LS remains on top of the deck.
2 & 3. X counts all brigades on good cards in battle, so Heroes and Enhancements. Brigades are not double counted, and rainbow is all 9 good brigades (blue, clay, gold, green, purple, red, silver, teal, white), so X is 9 if there is a good rainbow card in battle.