Ability to only allow certain content to be added between a range of dates
I would suggest looking into the Rules module for this.

Using this module, you can use its Condition feature to:


Check the date ranges that you specified
Check what content type is being created
Check the current logged in user's role if it's the permitted user role to create a content type


Based if these conditions are met, you can then add what event or message for this matter to display to the user. You aren't also limited to creating one rule but you can create multiple rules based on your conditions.

Hope this gives you an idea and solution.