A website framework needed for easy administration

I'm looking to create a one-stop website dealing with international real estate, travel and investment. I would want users to sign up to be able to view the site. While it will need to initially be free, I'd like the option to convert it to pay by paypal at some point. My site would need to be easy for me, a novice, to administer. I'd like it to include the following: 1. A blog section. 2. A forum discussion section. 3. A section for classified ads. 4. The ability to run pay ads/banners. 5. A section where I could create news articles, seperate from blog posts. 6. The ability to create numerous categories and subcategories for news articles and blog posts. 7. The ability to easily upload multimediate (photos, video and audio) if necessary to the blog and news posts.