Thats a detailed post, but I can only provide a brief pointer. Any database thats lightweight can serve your needs like derby or MySQL, but most of your requirements map into a lot of application/UI logic/flow. Since you mentioned web enabled, I think your options are down to php+mysql (or anything that you are familiar with like ruby on rails). As for the rest there are enough AJAX libraries like jquery that gwt toolkit that give you lot of UI functionality that can be tied to the db backend.
But I do see a contradiction, where you mention building an executable form of your app.