do you mean dhcp-v6-server... wan6-client? you haven't really stated your goal clearly ( read up about ipv6 basic knowledge ?)
depends on your environment goals
Same as above
There are quite a few threads covering most of these options.. albeit not in a 15 step hold your hand format. Although as goals and environments vary... devising a "suit all" oversimplified set of steps in unrealistic. The luci options are mostly toggles... A picture tutorial is kinda mute.
While I think your intention on having clearer options for applying common setup scenarios is valid. Expecting some picture guide that will meet your scenario is way unrealistic. And at the end of the day... more than half of your issue is a lack of knowledge on the fundamantal underlying concepts... which are not really openwrt specific.
Sadly, many people seems to forget that at one time, they also didnt knew anything or very little above a subject and the simpler and clearer guides helped those people understand the matter at hand and expand on it.
You are right, I will tackle each of those issues on other threads and articles.
So going back to the main "issue", I think that there should be more info and yes, guides, from a Luci perspective, since not everyone learn in the same way.