If they were hatchlings when you got them, you still have a little while to go. They typically don't start laying until sometime between 20-24 weeks. Rouens aren't one of the most prolific layers, but you might get enough this year to make a clutch they'll set on. Since they typically lay quite a few before they start setting, and it takes about 28 days for them to hatch, that would put you into mid-late October at the earliest for the babies to come. Since it's probably already getting chilly in northern Indiana by then, you might end up needing supplemental heat for them for a few weeks.
It's very hard to force them to lay their eggs where you want them unless you lock them in. Rouens typically lay in the morning, so you can control it to some extent by not letting them out of their pen until mid-morning.
If neither of yours goes broody after they have a clutch, yes, a broody chicken is fine. However, Rouens will usually set on their eggs. Just remember that they decide the size of the clutch they want, and there's nothing you can do to force that decision. I've had ducks that weren't satisfied with the size of their clutch until there were 16-18 eggs in it. It really depends a lot on the individual duck.
