Wordpress Website Edits Required

I have a unique / custom wordpress website setup and need a few changes. The site is based around the WPGROUPBUY Plugin and there are massive customization throughout the entire site. I need the following 3 changes: 1) A user can mark a voucher as "used" -> This button is ajax and i need it to request the user clicking the button input an amount/value for the deal they have purchased. This value should be assigned to the individual voucher purchased within the database and also display on the current sales report for the vouchers 2) Where a merchant adds an offer to the website i need the basic wordpress editor added to one text area. The function which gets the text area to populate is a looped array and is this one: $fields['description'] = array( 'weight' => 2, 'label' => self::__( 'Offer Description' ), 'type' => 'textarea', 'required' => TRUE, 'default' => '', 'description' => wpg__('Give your client more details about the offer.') ); 3) When a merchant registers on the website their business -> I need them to beable to select what category their products would suit. I do know which files are relevant to which within the system, need a competent person to do this and is able to understand if i talk them through the system and how it works once selected