Is my plan for a 'post coronavirus' world doable?

I think I heard on the radio something about identifying wrist bands for people who have had the coronavirus and recovered so they can do just that I guess. Then I suppose a thriving market in counterfeit wrist bands would spring up. This business might resurrect the idea of everyone having an identity number on a database again.

No. You still can be re-infected.

Yes, herd immunity is the endgame.

"On 27 March 2020, Chinese scientists reported that as many as 10% of those who have recovered from COVID-19 and tested negative, tested positive again."
https://en.wikipedia.org/wiki/2019–20_coronavirus_pandemic
https://www.npr.org/sections/goatsandsoda/2020/03/27/822407626/mystery-in-wuhan-recovered-coronavirus-patients-test-negative-then-positive

No. Too little is known about the viruses and the body's response to it, to put any part of your plan in place.

Nobody knows exactly why some people have no symptoms and others go into multiple organ failure and die, and one possibility is that there are different strains of the virus. And that having antibodies to a mild strain of the virus will not necessarily give a person immunity to the deadly strains.

Another issue is that it is the nature of viruses to constantly mutate, and during an epidemic they reproduce so actively that the process of mutation and changing into different strains is speeded up, and when viruses mutate into different strains then the antibodies from the original virus might not work against the new forms. That happened during the Influenza pandemic of 1918-1919, the virus mutated so quickly that people who'd survived the less-lethal disease of 1918 dropped dead of a different form in 1919.

So, no. You can't assume that anyone who's survived a mild form of the novel coronavirus is safe from future infection, or that such people don't need to follow the same precautions as everyone else.

you should volunteer to work in a hospital or nursing home.