Customization of WooCommerce plugins

I need to evolve already available plugins adding new features. Please don\'t be scared about the long description, it is just to avoid misunderstanding: - add the possibility for the store manager to set a % discount on the overall cost if the user subscribes to a product instead of simply buying it (subscribe all the things plugin) - add a sync renewal date for the subscription (subscribe all the things plugin) - add a free trial period for the subscription (subscribe all the things plugin) - allow the store manager, when adding products, to specify one shot products and recurring products through a [login to view URL] the customer subscribes to the composite product one shot products will be shipped only in the first shipment and their cost will contribute only to the subscription fee while recurring products will be part of the subscription and their costs will contribute both to the subscription fee and the recurring fee (composite product plugin) - allow the end user to switch subscription through a specific button in my account page even if the subscription is not made of grouped products or variable subscriptions but is a composite product. If the user clicks on the button he will access a page with the composite product he has already bought (actually only recurring products will be visible this time). The user can change the configuration of the product (e.g. quantities, selected components, components variation,...) and when he is happy with the new configuration he can proceed to the checkout. After the checkout the user will receive an email to confirm the switch (the standard email that is sent after a subscription switch by the subscription plugin) and an update will be sent to the payment gateway (Braintree) in order to change the recurring fee. During the subscription switch the use can also change the frequency of the subscription in case more than one subscription plan is available (subscription plugin)