I followed the links to the original sources.

Your first one comes from "The Straight Dope". It's an entertaining place for odd facts, but I would not treat it as a primary source. In any case, when we read about Cecil's attempts to clear the matter, we eventually reach this point:

>I called the Animal Medical Center to see if this possibility had been considered. The original authors were long gone, so I spoke to Dr. Michael Garvey, head of the medical department and current expert on “high-rise syndrome.”

Dr. Garvey was adamant that the omission of nonreported fatalities didn’t skew the statistics. He pointed out that cats that had fallen from great heights typically had injuries suggesting they’d landed on their chests, which supports the “flying squirrel” hypothesis.

So while technically true that this point was raised in the not-entirely-primary-source article, it was pretty much dismissed by the expert interviewed for that same article. When pressed, apparently Dr. Garvey allowed that reasonable people could disagree, but the fact that the expert falls on the "it's wrong" side, this point should probably be taken with suspicious eyes.

Your second one is more interesting. There have been different studies over the years and in some of them, we do get reports of more serious injuries in cats falling from higher places. In others, there is a dramatic decrease in injuries. As far as I was able to gather in a cursory look through the data, this is still a completely open question as to which data is more representative. Perhaps someone has a metastudy on this.

The nature of the injuries changes dramatically, though. At higher distances, cats can prepare themselves, get righted, and loosen up their legs for landing. The injuries tend to be more in their chest cavity. At shorter distances, the injuries tend to be more of the "broken limb" variety.