All Stores will open at midnight, with that said there may be the odd mall that will not allow it. Contact your local store, they know by now.
Disney does not print adds nor do the Cast Members know what the deals will be. History tells us that midnight to 10 will be 20% off of everything (excluding tickets, media, gift cards yada yada). Scope out your local store, look around. The things stacked in the windows and floors will most likely be big sale items. Those are also the things that tend to sale out that day. Luggage sales out pretty often then too. Listen to the Cast Member, if they say to get it now, they mean it. If they say wait, wait.
Right now there are $15 toys and $20 Buzz, Woody and Jessie toys. Get those now. The big singing dolls (brand new) are not on sale and are unlikely to be on sale but at the rate they are flying out the door get them NOW! All ToyStory things are in high demand, I'd get them now if you have a kid that is going to go into meltdown without it. Toddler dolls, don't get them DAT, they are always a better deal after!
Any other questions?