Create and Opencart 1.5.6.4 module

I need a module making for opencart 1.5.6.4 - module is for admin side only - and idea is based on group membership. I want business customers to be in their own group but their membership will be based on the date we admins add them to the user group and expiry could be custom but for example a customer signs up for business Account our admin adds them to business group so that date becomes their start date of the membership - membership depends on the condition that they have to spend £50 each month and if they do they will get an automatic 20% discount at the checkout. This module will have email reminders which we should be able to set say after 3 weeks if haven't placed an order of at least £50 they will get a reminder that they haven't and their membership will expire at the end of that period. All the business group will show in a list where their membership start and end dates will show with sorts and filters. At the customer account side can we show the group name with customers logged in name - and also show their membership details expiry etc etc So that's the summary of it all. Thanks