Moodle Assignment Activity Customisation

I am after someone familiar with Moodle 2.0 to design me a custom Moodle activity based on the standard online text assignment activity. I need an online text assignment activity that allows multiple questions and the ability to resubmit. Currently I use the quiz module but it doesn’t allow students to go back and resubmit within the same answers, and I need this functionality. For example, I might ask the student three questions. 1. What colour is the sky and why? 2. What colour is the grass and why? 3. What colour is wood and why? They type in their answers, one text box per question, and then submit all. I come along and I want to be able to mark a question as correct, hold, or not satisfactory. This then displays to the student when they review the task. I then want an overall feedback box for all of the questions - this is so I can ask them to resubmit (eg Q1 they only told me the sky is blue and not why) as well as provide feedback. They can then resubmit their answers by editing the original ones, and I can come back and then mark the question correct (or not satisfactory as the case may be). I want to be able to do an overall grade once all the questions are correct (they will always have to have all questions correct to pass)– eg give them a pass, credit, distinction or not satisfactory (this can be from the standard moodle letter grading system). The system does not have to recognise that all the questions have been marked correct - the teachers can do this, unless it is very easy to implement. l My timeframe to have this in a workable activity is by 20th December 2011 at the latest. I have attached a PDF of what I envisage the activity looking like on screen. All elements are taken from existing online text activity.