Hello,
I understand your need to develop a custom Joomla!-based application, please be sure that I will use all my knowledge to deliver a powerful yet simple extension, as expected, if not better.
Please note that I'll need to know more about the current system information, including PHP version and Joomla! version too, as well as other requirements, hence a system login will be essential for analysis.
Let me suggest to deliver the project as described in the milestones area, IMHO this will help you track the overall progress effectively.
Additionally, I will also provide 1 year of support, including a user manual and email support, incase you needed any advice, tutorial, or even fix or added feature.
Furthermore, the developed application will be licensed with the GNU GPL, except if you want something else.
Please note that your cooperation is vital to deliver this project on-time and with the expected quality level.
Never hesitate to get back to me if you have any inquiry, I'm always more than happy to help.
Kind regards.