There is MUCH to unpack from your OP . . . it would take me a couple of Seminars to wade through all of it in order to do justice to what needed to be divulged & elucidated.
Beginning & maintaining a business as a Signing Agent isn’t a sprint, it’s a marathon!
Certainly, I feel your frustration.
As you already are cognizant, there is a very large difference between being an employee and becoming a business owner.
As a business owner, from the onset, you’re going to be pretty much flying solo; that is, unless you have a family member that is within this business sector. There are no Manuals of Desk Instructions [MDIs] as one may find as an employee nor any more experienced fellow employees there to train you.
The standards of practice that you’re seeking are to be found by being curious and seeking training & certifications on your own as a professional business owner who strives to provide professional services to your clients.
I can strongly recommend a comprehensive training program that also has an option of mentorship with a proven track record of success. I’ve successfully completed a myriad of training courses/programs through about ten different training organizations. The one that has served me the best over the years has been the Notary2Pro Training & Mentorship. I’ve successfully completed all Carol’s certifications. If you’re seeking guidance & insights that are broad-sweeping and that will steer your course appropriately covering all the topics for a successful business, it’s Carol Ray’s team at Notary2Pro hands down.
DISCLAIMER: I’ve paid the full fee for all the training I’ve successfully completed with Carol. I receive no compensation or remuneration of any kind for sharing my experience utilizing what she taught me.
======
My personal experience:
When I initially started performing this work, it was unequivocally clear and painfully obvious that if I wanted valid, trustworthy training that I’d need to find a professional training program. The existing business owners explicitly stated that they saw others as the competition.
At that juncture, I successfully completed MULTIPLE training/certification programs including Notary2Pro & NNA and many others. I have extensive experience in skill sets that require certification and recurrent evaluation tests; i.e., I’ve maintained my Project Management Professional [PMP] certification for more than 20 years. So, I understand what it usually entails and the elements that should be included within a comprehensive training program.
Regarding the NNA training specifically, it’s lacking across multiple topics & categories. Many NNA “graduates” choose to take additional training courses elsewhere, because they sense they’re insufficiently prepared. Their primer has errors throughout. Their hotline is less than reliable for accurate responses.
In my experience with undergoing the multiple training programs for certified notary signing agent [CNSA] certification, hands-down without question, Carol Ray’s Notary2Pro training programs are optimum in this industry. I’ve successfully completed ALL of the multiple training/certification programs that Carol offers through her company Notary2Pro. Her programs are thorough & detailed. These also prepare the business owner to operate a business. In addition, she offers Mentoring services. I found those to be excellent & INVALUABLE when I was initially starting out in this business sector. The prices are surprisingly reasonable. 
I’ve professionally compared the training/certification programs available at Notary2Pro with the others I’ve successfully completed. The ONLY training/certification program I recommend is Notary2Pro.
A list of companies that hire Notary2Pro graduates (with minimal or no experience) is provided to successful course graduates. => This list is pure GOLD! Study up, refresh your notes, & let Carol know when your initial few signings are scheduled. She is a wonderful mentor & can be on standby in case you encounter difficulties or have questions during your first few signings. She’s the Best! Her support will help you Build your Confidence in providing this service. 
In addition, Notary2Pro works diligently to keep this list up-to-date regarding vetting and viability. As we all know, some reliable clients can encounter financial difficulties and that, in turn, can negatively impact CNSAs directly.
Of course, your best bet would be to visit their website at https://www.notary2pro.com/ , research, and make the choices appropriate for your situation. The training programs by Carol Ray are comprehensive & thorough. 
P.S. I receive no compensation or remuneration of any type or kind as a result of my first-hand experiential review above.
P.P.S. As Carol has recently passed (February 2022) from our earthly plane, reach out to others on her team please. You’ll benefit greatly as a result.
======
In addition, here are a few threads that are in support of your aims:
