there is no real “read-only” access for resources as resources can be invited to calendar events similar to any other user.
But you can restrict, that users can not ignore conflicts or set the status or the resource to accepted.
In general you grant read resource and read calendar of resource to all users, which need access. Edit resources and direct booking permission should only be granted to a small amount of users. Edit resources allows to edit or ad new resources for that category. Direct booking permission allows to change the status of the resource in a calendar event and new events will be set directly to accepted. If a user don’t have a direct booking permission, there is also an email generated to the resource admin, to let him know, that there are new events in that category.
There is no difference in that regard between community version and EPL version