Can I batch download invoices as PDF files?

No. There is no batch option to download multiple invoices as individual PDFs. However, as a workaround, you can send them as email attachments to yourself. For that, select the invoices in the list view and then click Actions > Email > Other. On the Compose Email screen, specify your email address in the To field and click Send Message to receive the invoices via email. Check CORE Help Center for details.