For inserting new Projects (or Template), the native Kickstart functionality @RandyRoberts mentioned will do the job.
As you mentioned "template adjustments", however, I invite you to consider our Excel Updater solution, which does updates (and inserts).
Our Synch Template solution might also be of interest, too: it allows you to use Workfront Templates to create projects, periodically adapt their tasks as things change (such as "new improvements to the existing Templates via Excel Updater"), then synchronize those adjustments out to their projects.
We do this using Workfront Fusion. Bulk import 250-300 projects for the quarter with templates attached, portfolio, program attached and custom metadata.