Build a myspql/ php database program for managing property with web portals.

Hi, Background: Most property management software runs on either access for small needs or mysql/php for larger needs. Comparable online programs are propertyware and rentmanager. We want to develop a program similar to the two above. If you are familiar with the above, that may be helpful. I do not know if there is open source code already available for this type of project that can help in its development. Any suggestions? Key elements: Web interface for (us) as well as tenants, repairmen/vendors and investors. So that's 4 interfaces. Various interfaces have various permissions and ability to run various reports, make payments etc. Various database tables: Properties portfolios tenants leases vendors Lenders/loans utility companies tax authorities work orders income/ rent payments/ credits payments/ expenses/debits I am sure more will be needed. Any suggestions? We need automatic billing and a calendar system to keep track of rent payment due and paid, charge late fees after a certain point. Waive late fees etc We need calendaring to keep track of tax payments and insurance payments, other bills we owe etc We need to be able for tenants to pay online, example [login to view URL] integration. We need for prospective clients to apply on line and to do background checks, example [login to view URL] integration We need it to keep track of financial transactions in relation to the properties. We need to be able to integrate/import our information to the online quickbooks and bill pay. We need to be able to make bill payments online, such as through quickbooks or another source . We will need various forms and reports. We will need a clean user interface so employees can easily determine how to work the system. Any suggestions are welcome. Price is negotiable. After development we will need to have access to your assistance to make changes, fixes, additions. So a monthly fee afterwards is negotiable. I put it in small project since I suspect there is code available but if it is not, you tell me what it will cost. Make offer. Thank you