"Typecast" just means that there are specific characteristics for those characters and they will adhere to them (i.e. Snow White will only be a really fair skinned girl). A lot of theatre auditions will put typecasts out for specific characters, like the young ingénue has to have a youthful look.
FeFe- There are a lot of factors involved. If they fit you for a character that they are currently looking for, you could get casted then. If not, it again depends on your character and the time of year. If they think you would make a great Cruella, but you auditioned in January, they probably won't add you to the pool (this is a list of people who have been approved to play certain characters but spots are not open for them yet. It only holds your information for six months) because they won't need Cruella before your six months are up. But if you're fitted for a character like Belle, they might need her before six months so you might get added to the pool.