Extend WordPress Events Manager (Pro) plugin

The requirement is to extend the WordPress Events Manager (Pro) plugin ([login to view URL], [login to view URL]) in the following ways: 1. Change coupons ([login to view URL]) to work per ticket type, rather than per event and add the ability to view coupon usage. 2. Add functionality to initially create a list in MailChimp and subsequently populate it with the name and email addresses of registrants, as they register for an event. 3. Add support for either PayPal Payments Pro or 2Checkout – to allow the event registrants to register on the event site, without being taken to the payment gateway site. 4. Optionally, add functionality to initially create a list in Capsule CRM ([login to view URL]) and subsequently populate it with the name and email addresses of registrants, as they register for an event. As Events Manager (Pro) is updated frequently, the above would need to be coded so as to still work with future updates of the plugin. I understand the plugin to be fully object-oriented, so I am hoping this is reasonably straightforward. Please consult the Events Manager (Pro) documentation ([login to view URL]) before responding. In your response, please indicate: - level of experience with WordPress plugin development/extension, - a description of any previous related work, - a rough time and cost estimate. Immediate start. Thanks.