Trad pub authors do not do endorsements for pay or as a "you scratch my back and I'll scratch yours" thing, but some of them do know each other and like each other's books. Those endorsements you see on hardcover trad books were sought by the publisher, not the author, in probably 99% of cases.
As for the rings of indies doing it, they are not naive; they know they are breaking the Amazon TOS, and they make it hard for the rest of us to sit on our hands and wait for the honest reviews to come in, as B.L.Alley notes.
When I first started as an indie, I was naive and desperate for reviews and asked my beta readers to post precis of their crits of my book--warts and all, just please post something. At the time I did not know this was against Amazon TOS. Once I learned that, of course I never asked anyone again. My ARCs go out with a very soft "I hope you enjoy it" kind of message and zero demand for a review.
The problem is, as readers, we tend to look at the number of reviews/ratings as the social proof. We don't go looking at the book's ranking and we may not want to get sucked into the story by reading the Look Inside. I myself have checked out new books from newsletter ads, seen that they only have a handful of positive reviews, and moved on. Not that I thought the book was a loser, but I felt I could wait until there were some 1-star reviews to balance the praise and give me a grasp of the book's failings. A harsh truth, I'm afraid. This is why I'm willing to use NetGalley from time to time, so there can be more balance in the reviews--NetGalley readers feel no need to be nice to an author.
As for contacting that old school friend who rose to fame, you guys should do it. Amid all the chaos of their new life, they probably would be happy to hear from an old friend. Just say hi and congratulate them. It could mean a lot to them, because inside, they're probably still that person you knew way back when. Aren't we all still ten years old and trying to prove something? Proof we did it would be fabulous.