Hello,
We have done a similar and related project earlier and we know how to implement this concept. We agree with all of your concerns, and that is why we have planned to work with open source technologies so that we can scale up the project whenever you need.
Our Demo: [login to view URL]
Technologies that we will use: PHP, mySQL, Codeigniter Framework, Ajax, JQuery, Bootstrap 3.0, HTML5, CSS3
Security is an important factor so we will use MD5 and SHA Encryption techniques to encrypt confidential information within the database to safeguard them from hackers, also, privacy settings will be provided within the user panel and admin panel as well. Also, private information will not be visible to others until a user wants to make it public by himself.
We will provide Paypal and a Credit Card processor which will work on split payment basis.
The design: as I mentioned we will use Bootstrap 3.0, so your website will be 100% responsive, that means it will work just fine with all type of devices.
I understand your condition of putting the property image by yourself, or we can also give each post by user a moderation by you, so it will only be visible when you approve it.
You will have a section, which will explain to you how to use the admin panel and the website.
Future improvements and scalability is endless, as we're working with open source technologies.
I understand that you will test it with fake users, I agree on this.
Let's discuss it further.
Thanks