Hi,
Your requirement is quite clear and straightforward to implement so no questions about the features. The tool will have a simple interface to list the transactions. I'm planning to use a grid component, e.g DataTables, to list and manage the transactions in the web app. Through that interface you'll be able to run all the operations mentioned.
As you may already know this'll utilize web connector. I'm sure your QB version is more than ok for this but it's no harm to remind that you need QB Premier & Pro 2002 or later, Start Edition QB 2006 or later.
Anyway, I'm not sure if you have any specific language to implement this but I'm planning to use php. If you have something else in mind please let me know. I expect this to take around 10 days.
Thanks
Ibrahim