PayPal Pro for WP re-write (reposted)

We have a Wordpress plugin for taking payments via PayPal Pro. It has a number of bugs and was written really badly. We want a total re-write of the code with the same functionality. The plugin works as a gateway. 1. An e-commerce website sends an HTTP post to the gateway with price, quantity, user info and other information. 2. The gateway presents a screen to the user to fill in payment details, credit card details, etc. 3. The data is posted to PayPal Pro and the response shown to the user if there are any problems. 4. If the transaction was successful the user is redirected back to the e-commerce site. 5. An independent confirmation of the transaction results is sent to the e-commerce site. == The End == You can find out more if you look at the source code: [login to view URL] There is a number of problems with the plugin that we need to fix. 1. The delivery address is passed to the payment page, but not to PayPal. 2. The email address entered on the payment page is not passed to PayPal. 3. Poor error handling. Need to check if PayPal reject the transaction and give a meaningful message to the user. Some special conditions: 1. You need to work with SVN (check out, then check in, takes 10 minutes to set up, we use Google Code) 2. Any changes you make must be quality code with comments 3. We do not provide a development server - you need to use yours 4. You will need to allow up to 48hrs for testing before the code is accepted (we test in our own environment). 5. We would prefer someone with a long term commitment to support the plugin as there are a number of features we want to add in the near future. We are expecting bids at a lower range.