WHMCS Adjustments/modules needed for desired results

I need either a single module, or separate modules for WHMCS. It must work with the latest version, and mustn't get overridden during upgrades. Ajax enabled admin theme that will allow you to quickly add a new line item to a quote without having to press save and wait for the page to load again. A module that will allow the ability to split a invoice to 2 or 3 clients A module that will allow you to attached additional files to a quote and a manual invoice (not a recurring one). A module that allows you to save custom products that were entered manually when creating a quote/invoice (in other words if I type a line item into a quote or invoice, after I save it there needs to be a little button/icon next to it that says save this product). ONLY SERIOUS FREELANCERS Payment structure will be a 100% milestone payment, 25% released after each function completed. Freelancer must be prepared to provide 6 months support once project is completed.