Magento is capable of bulk import as well as export. The way I recommend you do this is by:
- first creating a sample product,
- then do a bulk export (even though you'll only have a single product) via
System>Import/Export>Profiles and select Export All Products.
- You can then retrieve the CSV file from
/var/export.
- Open the CSV file in your preferred spreadsheet editor (OpenOffice/LibreOffice Calc, Excel, Apple Numbers, etc.) and use the sample product's entry as a model to create all of your other products. Remember to put a
/ before your image filenames.
- Upload your images to the
/media/import directories.
- Finally, go to
System>Import/Export>Profiles and select Import All Products and upload your new CSV file and save.
- After saving, you'll be able to select the uploaded file from the dropdown list and run the profile, which will create all the products and load the product photos.
However, I don't recommend you use randomly generated product IDs. Like Matt says, any decent web store will generate these codes for you, and they'll be consecutive numbers, which would be more logical than random codes.
The SKU field is only used if you already have a cataloging system in place for your products. For instance, many businesses will already have a system for cataloging their products for stock-keeping, ordering, distribution, etc. before they migrate to Magento. They would use the SKU field to bring the system over to Magento.
Otherwise, it's more important for you to specify a user-friendly (thus search engine friendly) URL key for each product. I believe Magento will try to generate one automatically from the product name, though often auto-generated slugs are not optimal.