Rule 8-1:Nine (9) players are needed by each team to start a game. A team can finish with eight (8) players, but not fewer than 8. Forfeiting team takes a loss. Non-forfeiting team gains a win. If both teams fail to field 9 players, both teams will get a loss and Rule 2-2 sanctions will be applied.

Rule 8-3: Players cannot be borrowed during playoffs.

Second question. If you do not bat 9, the ninth spot in the order is an automatic out each and every time that spot comes up. There is no condensing of the order.