1. 1 & 4 fire a turn apart at the same point/timing mark on the flywheel, and 2 & 3 fire 180º from there, halfway around the flywheel. (1 & 4 crank throws are on the same plane, as are the throws for 2 & 3.)
2. Spark occurs when the breaker points OPEN and the statement "the rotor is slapping around so much that the timing isquite jittery now" is NOT valid. However, wear/looseness/slop in the distributor gears/shaft/advance mechanism CAN casue the timing mark to move around.