Wordpress customization

The job is to Customise a Wordpress theme written in PHP. The theme is Freelanceengine (FRE) by Enginethemes, which is pretty good as a starting point but the user support is slow and they do not offer customization.

PHP skills essential and, ideally, you will have worked on FRE before. Specific tasks:
+ Payment gateway integration (probably SagePay, possibly BrainTree) with ability for recurring monthly payments
+ Create function to add free credits to user accounts without visiting payment gateway
+ Restrict users to 1 free plan
+ Create function to add fields to forms (freetext and dropdowns)
+ Integrate user registration process with user profile creation
+ Create "return to page last viewed" ability after registration
+ Simplify category entry by user so that they are offered initially a short top level of general categories, followed by specific options.
+ Create real time match of catalogue of categories while user enters search terms
+ Combine two search categories (to avoid user having to search twice)