Hello,
Let me answer in easiest way I can by breaking it down part by part.
Could you confirm that the billable item PDFs will be attached to the customer invoice for them to click and view? Yes. If you checkmark the box that says "attach to email" then any attachments that were included on the billable expense you created, will be able to be seen by the customer when they view the invoice. In order for this to be a default, you might have to manually select it the first time and then after that it will remember. I'd recommend trying out with a few test transactions that you email to yourself to be sure.
Can I choose to leave off the "Pay Now" button on the invoice? I want to look as polished as possible and not leave any question in the customer's mind that everything flows smoothly behind the scenes without them lifting a finger (unless they want to).Once you have the clients billing info saved in their customer profile, you can uncheck the boxes to allow them to pay online. This will change the link from Review and Pay to Review and Print. They won't be able to pay the invoice online by their own hand.
Also, do you know of any software that automates this and integrates with QuickBooks? I've been searching for two weeks including on the QB website and haven't found anything. You can look into 3rd party apps. Some claim that they can add more automation into tasks in QuickBooks Online. I don't know of any off the top of my head. Just keep in mind of a couple things. They may add more functionality but if something isn't working correctly and you're using an app, Intuit support will be limited in what troubleshooting they can do depending on where the issue lies. I would ALWAYS recommend thorough testing by sending yourself emails and transactions to make sure everything is flowing correctly. Like Scotty on Star Trek once said "The more they overthink the plumbing, the easier it is to stop up the drain"
Side Note: Also, (and I'm sure you're already aware but never hurts to make sure) remember that you'll need to create a recurring invoice template for EACH customer.
