I am providing a form to a user to create a product. I want to provide a few fields from a product type, along with some normal Form API input. Example, I only want them to specify the price and SKU. I want the submit handler to take care of creating the title name and any other fields. In this case, a product lives as product entities and as product display nodes. I want to present my user a single form to create and manage products.
I looks like I should be able to do this with the Field API, but I just see how to attached all fields from an entity. I just want to attach a few.
Am I able to do this with the Field API?
EDIT TO ADD MORE INFO:
For example, when a user creates a new product, they will enter a 6 digit SKU. Each product will have that SKU, with another 3 digits appended, specifying a category. I want the user to simply enter the base SKU, like ABCDEF, select category Y and Z, and the submit handler creates the products with the correct SKUs, like ABCDEF-0001, ABCDEF-0002, and creates the node display. There are also specific fields of the product type, so I need the user to populate the fields for these products, using the WYSIWYG filter they would otherwise use on the product create form.