I'm one of the authors of this piece, which was produced by a YC-backed non-profit trying to revolutionise careers advice (80,000 Hours). AMA!
For example, assuming that 'Work that helps others' is actually causative (and not that happier people tend to choose that work), what are the identifying characteristics of that type of work? What makes midwifery (from the article) more satisfying than say serving in a restaurant? Both appear to help others. Is it the magnitude of the help? The degree of personal engagement?
How can someone better identify 'Work you're good at'? Again, assuming it is causative (and not that happier people rate their own competency higher), how can someone effectively identify their comparative advantage? Presumably for career choice there is a strong effect of demand vs. supply in skills - I can be 'good' at snowboarding by most people's standards but have no chance of making a career at it. The advice on its own is not very actionable.
The article makes a common conflation of high achieving individuals with work satisfaction and yet the two do not necessarily match up (do we know that Steve Jobs and Einstein were more satisfied with their lives than average?) and these two examples from the article seem to not fit the 'Work that's engaging' criteria of 'Clear tasks, with a clearly defined start and end.' or 'Feedback, so you know how well you’re doing.', at least in the short to medium term.
Like I say, I think this type of research is valuable but I find little that is clearly actionable in my own life, with the exception of simple things like 'avoid long commutes' and from elsewhere in the happiness literature 'spend on experiences rather than things'.
We address one of your questions in a later article: how to work out what you're good at https://80000hours.org/career-guide/personal-fit/ (And beyond this, you need to make predictions - I think the book superforecasters is good on what to do there)
I'm specifically thinking of myself (and probably a number of other people here) who tend to throw "extra" income past a certain point into retirement. Would be curious as to how that affects happiness after reaching the age of retirement. (Apologies if in article, still finishing)
Some took a longer term view, in particular the ones on lottery winners.
Saving for retirement is obviously sensible. But I think the result will be the same - you won't be much happier retiring on $120,000 a year than $60,000 a year. What will matter at that point is having social connections and feeling that your work is/was meaningful.
However, I specifically asked about retirement because it shares some interesting characteristics with your supported findings.
A) Retirement accounts are intangible. I may receive pleasure and happiness from imagining the money I have in them, but believe it would be a hard case to make that I received true happiness from increasing them
B) Enabling retirement would seem to dovetail with the plateau effect. To wit, if I make $40k now, but am unable to save enough to make $40k in retirement, my happiness would plummet if I ever retired. If I make $60k now and save enough to provide $40k worth of retirement income, then my happiness would be substantially improved. Therefore that +$20k has a secondary effect of making me much happier later in life
I doubt it would change the findings, but if true, might shift the numbers a bit.
Money does make you a bit happier, but most readers of HN are among the top 5% of income earners in the world, so it's not the top priority for them, on the margin. You can get more mileage by focussing on other things. I also think affective measures of welfare are more reliable than evaluative ones. But it's a huge issue that I had to write many thousands of words to cover properly, so check out the full article and see what you think.