Let me start by saying I have worked at 3 WDW resorts front desks over the last 10 years... You have nothing to worry about.
If you booked a prefered view you "should" get one...sometime circumstances arise that would cause them to downgrade a reservation but that is not a normal occurance. You don't have to worry about being left with a king bed. Since you are traveling with a junior, it will show on the reservation, they will not put you in a king with that type of party mix. As for not having rooms when you arrive. 10pm is still early for arrivals at the All Stars. Because they have such a high occupancy they tend to have a lot of late arrivals. Where other resorts may only have 5 or 6 check ins left at 10pm ALl Stars usually have a good 10-20 or so at that time. If there was a situation where your prefered room was not avalaible or something else was wrong with your room you could do a room change the next day. It is not the most desirable situation, but it is an option if things are not right. Again, with the All Stars I would not worry too much, 10pm is still early. If the off chance did happen and they were oversold, no rooms left, they would have already set up another hotel for you. They know very early in the day if they are oversold and will start calling other Disney hotels to make sure that they have enough rooms to cover the amount they are oversold. The All Stars will start with the other All Stars, then Pop, then the moderates, working there way up until they find a room for you, you would not be left in the cold. Even though it may seem like the other resorts are sold out too, don't worry. There are early check outs, cancelations, no shows, rooms find a way of becoming avaliable throughout the day.
