I agree with almost all of the advice here but there are a few exceptions to the uphill/downhill rule. Uphill putts on Oakmont spring to mind. In my experience, if you have a 10 foot putt that's 2 inch uphill it's best to hit it about 14 feet, even on tourney greens. Downhillers on Oak need a very gentle touch, straight uphillers need to be whacked. The rises and falls at Olympic just seem plain wrong to me, most uphill putts need hitting way harder than you think, the downhill ones a lot softer. I suppose Oakmont could also be wrongly mapped, I like the course though so give it the benefit of the doubt. Unlike Olympic.
I don't use any sort of distance % calculation for any of my shots to be honest, I play purely by feel and experience. I could tell you I played a particular shot about 1/4 inch less than full power but would have no idea what percentage that was. I use a formula for cross wind which I will also use to add or subtract power from a shot if it's a head or tail wind but applying that to the meter is purely feel.