Add features to Joomla Addfactory ads extention

I have a website that I am building where I use Adsfactory module for Joomla. Module is very good but we need some changes.. I can explain this much better but main points are: When user is buying an Add he now can pay with creditcard and Paypal. Need one more option, where user choose "Send Invoice" and an PDF with Invoice look is sendt to us and one copy to the user. This module has categories feature. Now I have One dropdown with All categories inn it..I need 2 more where I can choose first main category level , and then second subcategorie. There is payment module..We need to be able to offer user to but 2-5-10 ads fwith a discount..Then user has an credit with us regarding the amount of ads he has payed for. For the one that is going to do this, if he is able to deliver this fast and good there will be several more changes in the same module soon after this is done. I have all the sourcecode and module sett up. We all work online. So the person that works with this can live where ever.. Need fast response.