Automate CSV file into Magento for product stock/costs

Hi All I’m currently receiving tab delimited CSV feed files from a supplier with products I want to integrate into a Magento store. The file can be picked up from an FTP location which is updated every 30minutes. I want a module to be made to upload these products into the database. All my products have the supplier part number which I could use as the primary key. The supplier file is set out below:- Supplier P/N, Man P/N, Product Name, Stock, Manufacturer Name, cost, Description, category name I basically want a solution to the system to update stock/cost when a product already exists and create a new product when it doesnt. Also I want the ability to apply fixed category percentages to the cost so when the data is inserted the percentage markups are auto applied. A sample datafile can be supplied.