Build Some Opencart Extensions

Ok, I need 3 separate opencart extensions, All should work together and Ideally be vqmod, but this is not necessary A strict requirement. 1/ When logging in, A customer should have the option to be able to upgrade there order (We don't sell shippable products, but tickets so there order would not have shipped, hence why we can offer upgrades). You should only be able to upgrade your order to a product in the same category from which you ordered, and one which is of greater value. When a customer does this, there original product should go back into the stock inventory and the upgrade product deducted. 2/ Product option Enable disable (I believe this will be necessary for number 3...You may have another way to do this. 3/ Stock Allocation. We would like to sell a product option, and once the inventory level reaches a defined value (Set in admin) a new product option will be enabled. The admin should be able to define the product option to come live in the admin system....So (When product option A reaches a stock level less than X, Product Option B will be enabled). Please reply to this Project by starting with "Opencart"...If you don't I'll assume you didn't read the project description. I would also really need the freelancer to have a very good grasp of English and available to talk.