I don't think you want to use Spree for this. Just because it includes the "piece" you want for your own puzzle doesn't mean it is designed to operate independently of Spree. It is incredibly easy using rails to create a simple "read only" catalog that other users can update and maintain. I would suggest spending some time to get familiar with rails and its pros and cons pertinent to your use case.
Spree is designed to be a developer orientated e-commerce platform. It has a 'catalog' as you would describe it as a requirement for its primary purpose: The exchange of goods for money. This is not your use case so spree will not help you with your goals.