Magento Custom Category Development

First, we only want to work with someone that specializes in Magento and has built custom modules and code for Magento. Would also prefer someone that can complete requirements on own server so we can see how customization functions before changing code on our site. We carry parts for swimming pool and spa equipment. We make it easier for our customers to find the parts they are looking for by using a schematic view image of the equipment they need to repair. On these schematic views each part is assigned a key # that corresponds to the #’s on the schematic image for easy reference. Here is a link to an example. [login to view URL] Here is our problem. Some SKU/Parts are used in multiple pieces of equipment so they will be shown in multiple category / schematic views. But, a SKU might be Key #1 in one category but Key #4 in another category. What we would like to have done is get a customized category view for our schematic parts categories similar to this layout. [login to view URL] Then, in the admin section we will need a way to assign the proper Key # to the SKU on a per category basis. Then, when the customer clicks on a certain category / schematic view the SKU/ part assigned to it will know what Key # to display on that category page. Some other things we will need is to have the ability to import / export this data via excel spreadsheet. The category view page will need to be sorted by Key #. That way Key #1 is first, followed by #2, #3, etc. We would also like to give the customer the ability to add multiple parts to their cart at one time. So if they need 5 or 6 parts they don’t have to add one item to their cart then go back. In short, we need to display a certain set of product information on a per category basis. So we need to be able to display certain information for SKU #ABC in one category, but display a different set of information for the same product in another category. Please contact us with any questions.