magento - import categories and products

I'm looking for someone who can help me to get a list of categories imported in magento. For this i need an example file of how the categorie info should be listed and then i deliver you the list with categories and categories info what you will import in magento. Also i need to have a lot of product imported in magento. This product are now in a x-cart database so the info should be exported first. Then there is the following problem: product options For example i have in x-cart shops lots of products what have 3 collors and 3 sizes. In x-cart database this is just 1 product. In magento for eacht option must be created an new product (9 is this situation) and then should be combinated in a configuration product. Also i need extra fields for products. I need a field for the warehouse location of a product. Also i need fields for sku of the company where i buy the product (this is different then the sku i use in the shop) and a field for the name of the company where i buy it and the price i pay at this wholesale company. I would like to have this field for 3 different company's (i can buy some products at multiple wholesalers). For this the core code of magento may NOT be changed so i need a clean easy sollution for this. I would like to hear how this can be done the best way. ONLY make me a offer when you now exact how to do this. So do NOT place a bid when you do not now magento but you think you can figur out how this can be done. Do not place standard bids but explane me in a message what your experiance is and how you are going to do this.