All Play just means your lineup faces every other lineup in the league each week, so top scoring team in a week will be 32-0, 2nd higghest scoring will be 31-1, and so on...that stacks each week so its like a persistent ranking table.
the lineups are start 1 at each position, then any 4 RB/WR/TE, so 8 players total, with 4 on the bench
give me a shout if there were any specifics, but thats the jist of it