No, they will not tell you when you check in. Ours have always been inside a brochure in the room. You have to look for it. If you can't find it you can call ext 8844 from your room phone. There is a list of the bounce back dates for the rest of 2015 inside this thread -
http://disboards.com/threads/just-got-back-no-bounceback-offer-was-going-to-book-for-sept.3390378/. The discounts were 35% off deluxe, 30% off moderates, and 25% off value.
There are also reports on that thread that the regular Disney discounts, combined with the Orbitz discount, will give you a better rate. For my bounce back at a value stay, the Orbitz discount would give me another $6 less per night, but I am planning to pay with Disney GC I already have, so I didn't switch.