If you got your birds through a hatchery, chances are, they are NOT show quality. Thats not to say however, that they would not do well at a fair as fairs are different than a sanctioned chicken show. Fairs are usually interested in production breeds, which are what the hatcheries sell mostly and the judge at fair will go by how filled out the bird is (for a meat variety) and how close to the point of lay one is (in a egg layer breed). It generally goes by body quality.
A sanctioned chicken show goes according to the Standard of Perfection (SOP) which are two books put out by the American Poultry Associatio and the American Bantam Association. This type of show does not want production birds, as it goes mostly by appearance of the bird rather than body quality.
So see, it really depends what kind of birds you have, and what type of show you are interested in showing in. If you want true show quality birds, you need to get them from a private breeder, not a hatchery like McMurray or Ideal. Be prepared to pay more for these birds, and that they will generaly be started birds and not chicks.
Your birds all sound fine for a fair, a silkie would work more for a sanction show, but if your fairs in your area do both kind of shows, they it could work there too. My county fair do not have "other breeds". If they do they are considered miscellaneous and are all judged together, and my judge here runs a egg farm, so, he admits, he knows nothing about the fancy show birds.
Yes, you should always wash your birds before a show, as a clean bird is better and will look better than a dirty one.
