A basic store is less than $30 a month, so not a major deal breaker if you ask me.

You could try it on a month to month basis. Give it 6 months and then make a decision.

Create your banner and thumbnail and set up your store categories.

I would suggest you read up on store categories either through Ebay help or just Google it. You'll allocate each listing to a store category, although if many all under the same type, you could bulk edit them.