Add Products to Interspire shopping cart

I need someone with experience adding products to the Interspire Cart through CSV upload. I have dozens of product lines to add to my apparel website. I want to start will a single product line that has about 35 parent products, about 20 color variations for each product and 10 sizes per color - total of abut 7,000 individual SKUs. I want each parent product to have all the color variations, sizes, pictures and prices available on one product page. To start, I want to take one product line and re-merchandise it on the site. Currently the site is set up to display all color variations as separate products and I want to consolidate all the colors under a single "parent" product. I have all the data you need, it just has to be reorganized and formated in excel for upload. Pictures are already loaded, but are available via FTP if you need them. Also when adding the products to the spreadsheet there is a field for SEO, you have to think of all the combinations of the product and add it in the seo field. You will need to submit a sample product that can be uploaded to show you understand how to do the work. If you get this project done quickly and the data is perfect, then you can have the project to do the rest of the product lines which is much much larger than this project (40,000-50,000 SKUs). I will also need regular maintenance 2-3 times/year to keep the site merchandised with the latest products.