It generally takes some practice to become comfortable not using a prepared checklist, but I encourage you to start now.
Auditing is supposed to be about verifying the effectiveness of a process. Have there been problems with this process? If yes, start there. Begin by asking too what is the goal of the process. What does good performance look like? (metrics, performnce measurement) Or, "What does winning look like?" or, "Who depends on this process going well? What do they need from this process?" (outputs)
The point I am trying to make is this: I don't understand the technical details in your procedure, and I fully expect your auditee(s) to not understand your questions as written. You can get your answers such as inputs, outputs, controls and resources by exploring the process with its owner. I can see some documentation is required by your procedure. You can ask for a list of clients, pick out 3 or 4 and ask to be walked through the process with these examples. Have a conversation. Ask questions in plain language: "What can go wrong?" and with the answer, "What do you need to do about that?" (This is plain speak for nonconforming outputs and corrective action.)
Audit process inputs generally take three forms: what you observe, what you are told, and what is documented. I think of it as a 3-legged stool that holds the process weight (controls); ideally there would be all 3 legs, but not all these three are needed or required all the time so I really hope to see 2 legs. If there is only one, for example the procedure exists but the descriptions and documentation don't align, there's a problem. If you are told 3 different things by 3 different people you need to learn which is correct; if the procedure is not correct that can become your focus. If required documentation is scarce, incorrect or haphazard, that stool leg is weak.
I hope this helps.