Ticket/order system

Hi Guys 🙂

I need to develop plug-in to WP and I’ve some related questions.

Use case:
1) User can create a “ticket” – that’s a form with many fields, and also can upload multiple files assigned to this form.
2) After submission script should send and email to user and administrator, with summary of form and generated unique link to ticket status page
3) On status page will be displayed details about ticket (data from form + urls to uploaded files) and ticket status. Also user can comment on ticket (automatic email to administrator).
4) Administrator can manage tickets via admin panel (view/edit data, download attachments, change status, comment on ticket) => (automatic email to user with notification about changes)

OK, now my questions 🙂
– Could you recommend me any similar plug-ins to read their sources and learn basis on existing code?
– How to generate and display pages with summary (is it possible to implement it without generating static pages for each ticket?)
– Can i use wp comments to provide comment functionality on summary pages?
– How to manage attachments (can I use any wp functionalities?)

I think that’s all on this moment, thank you for the answers.