Thank you for the kind words! I am glad you enjoyed this tutorial and found it helpful. Cheers!

Yes, you still need the original part because the derived part links back to the original. If you want to "derive" a part without linking it you can simply do a "Save As" on the original. The benefit to using a derived part is that whatever changes happen to the original file, those changes will be reflected in the derived part as well. Thanks for watching!

It depends on what you intend to do with the operation. Using the derive command allows you to control how you modify the base part. You can use it to consolidate multiple solid bodies into a single solid, you can maintain each solid body separately, or you can even convert everything to work surfaces to reduce file size. So for example, say you have a large and/or complex part that is incorporated into an assembly that goes to a customer. What you can do, is you can derive a simplified version of that part from the original (base) part and save it as a work surface while also removing some details that the customer does not need to see, such as proprietary design elements. This will reduce your overall file size and allow you to modify the original part as you see fit so that you get enough information to your customer (such as overall part envelope size) but you still retain some of the proprietary information. Of course you can still do a "File > Save As" operation, however, the derive command is a more powerful method that affords you greater control. Thanks for watching! Cheers!