I began manually imputing the category tree which is quite extensive is some parts with many sub-category branches. All the products that need to be imported have categories in the CSV file. For instance, there are 3 columns: primary category (root), secondary category, and sub category.
When I import these products, is there a way to tell Magento to create these categories in a branch setup that I specify? Or do I need to continue on with the manual input?
Standard Magento 1.x import does not allow to create missing categories during product upload dynamically. Therefore, the categories must be setup in Magento admin panel before product import itself.
If you do not want to create categories manually, there are extensions allowing create categories on-the-fly during products import or scripts to import categories without products first.