If you have the file from the distributor and need to update your store with products and products information on some timely bases, I can offer you the applications - Store Manager for Magento and its addon called Automated Products import.
Those 2 products in combination allow you to set scheduled update and each time period you want - for example each night at 3 am.
Also you will be able to set your own price-mark ups if you need to set higher price than your supplier provides you. Using offered applications you can directly via import assign products to certain categories. You can import all types of products from simple to complex (configurable, grouped and bundled). If you also need to import images from your distributor, the software will also handles it in case you have image URLs.
The software accepts .csv file format, but if you have Excel file, it won’t be an issue, since you can use save as option in Excel and save it in .csv for suitable for import.
There is 2-weeks free trial version of both Store Manager and Automated products import addon. You can download it here -
If you further decide to use the solutions, they are paid ones, but you purchase once and than use the license live-time.
Hope it is what you was looking for.