In most cases, using one of the existing plugins as a guide works very well.
RE: "type that uses a form with input fields to forward" Have you looked at Authorize.net plugin?
But then you need more or less the exact same scenario also. So many nuances today. At the least we can agree that todays docs are a bit sparse on these topics. Nop has to see the potential in having more devs catching up.
Also. I think everyone agrees that the difference between success and not is documenation and help. All the big systems like EpiServer for instance, has tons of docs and support.
Lastly. This is a good business opportunity. Selling these videos could be yet another revenue stream while generating more acive users (since many corps rely on docs to invest in systems).