First nice =! expensive. It's a subjective term meant to allow you to find your own definition. The whole point is one you seem to be in need of (don't focus on "specs" or "definitives" and just find a bed and bedding that you love. If it is more expensive then it's money well spent.)
Re: farmer v doctor- again you're focusing on the "detail" of the advice and while totally missing the point. The point of that advice is that prevention (whatever you personally define as such) and taking care of your long-term health is a far better option than waiting until something breaks.
You seem to want this advice to offer the exact recipe for a better life. You expect it to contain the scientifically proven facts. Unfortunately that's not how good advice works. Good advice gives you perspective while leaving the details up to you.
<mild_snark>
Finally most of the advice deals with this thing called "joy". you'll find that scientifically speaking there is no agreed upon universally measurable "joy" metric. In lieu of science I recommend creating your own totally subjective definition of joy and applying it to as much of your life as possible. I have no facts to give you as to why this improves your life so you're going to have to trust me... But it does. Vastly.
</mild_snark>
And that is the big picture that each piece of advice is offering you.