What should be primary online vehicle for information about activities?

I have been maintaining Facebook page for an NGO I volunteer with for past few months. While discussing our online presence, we came face to face with the question whether to start a blog or continue with sharing of activities on Facebook page.
Since we are part of a large organization, certain decisions are taken for us unless we can influence them with logical arguments. Desire for the blog stemmed from certain requirements such as:

  1. Our supporters or people who want to know more about the organization will be visiting our website. A blog on the website will give them a view of our activities.
  2. Not every one is on Facebook or likes visiting Facebook.
  3. Depending on Facebook to share our activities would mean that we are depending on Facebook’s policies. Recently we have seen that facebook is making changes which will adversely affect organizations with limited financial resources.
  4. We would have greater control over our photographs and archive of posts.
  5. We will be able to showcase important posts as we desire.
  6. Currently Facebook offers limited features. With our own blog, we will have access to many features developed by 3rd party or develop few according to our needs.
  7. People are likely to trust blog hosted on our website a lot more than Facebook page.

We are sure many organizations feel the need to decide between blog and Facebook page as their primary vehicle to share information about their activities. Could we have added anything further to strengthen our demand for the blog?