Im going to this one too
I'm assuming you're entering the main class? In this case then yes you will need to get shavings or cat litter, it's a change for mine too, they're usually on aubiose, but they don't seem to mind it!
You are correct in that anyone can enter, and no you won't need to pay anything other than the costs to enter your hamster. If you are a non-member you won't tbe able to enter certain duplicate classes like novice and the members points classes, but the main class and most duplicates you can enter.
You might need to hire a show pen? Robos are shown in syrian pens.
You'll need to give him a piece of vegetable, most pepole use cucumber or carrot, I usually cut a thumb-length chunk of cucumber and then cut that in half. I don't like to use carrot as it can stain! Benching is between 9 and 10, make sure your hamster is on the table by then. When you arrive at the hall the show sec will have the labels for your pen and a dog biscuit, and you can pay your fees then. The shows can run quite long, I'd expect to be there til about five.
If you don't fancy the main class you could try the pet class, that way you can show in your own carrier, on your own substrate, and ypu won't need to book in until the afternoon.
That's all I can think of for now!