Custom shipping extension for Magento

We are looking for a custom shipping extension that is compatible with Magento 1.8. This extension must be programmed using Magento best practices and must never modify core files. We have several shipping rules and situations that require an extension to replace the standard functionality. Details are provided in the attached document. We expect freelancers to read all requirements in our detailed document. Any questions or concerns should be clarified prior to bidding. If you intend to bid low and request more money later because you did not understand our requirements then please do not bid on this project.