Ravenpaw was popular with Queens, whom Tigerstar made sure to spread rumors among first whenever he was watching over Swiftkit and Lynxkit.
Firepaw sounds different to the other cats, which is one of the things that causes hostility towards him from others.
Cinderpelt is actually shown with her snail friends. She has a few around the Cleric den, but her favorite one actually comes inside, the rest just chill near it.
Sasha's time in Tigerclan is seen in more detail, and is explicitly included in the Special Book, Sasha's Family.
Volewhisper, Deadfoot, Barkface, and Rosetail all deal with chronic pain. Volewhisper's leg often aches and gets worse when he pushes himself. Deadfoot's got an old tail wound that can be quote uncomfortable if he is sat down. Barkface's hips give him trouble, made worse when he runs for his life during the Windclan Massacre. Rosetail has pain in her..."Wrist" joints. No injuries caused it but they're also behind her early retirement, along with her extreme grief. They all use different ways of coping!
Fernkit was born MASSIVE. She becomes an apprentice early, between Into The Wild and Fire and Ice. She's still close with her siblings and mom, though.
Cloudkit, while still fostered by Brindleface and incredibly close with her, is acknowledged as not her kit necessarily, but that they have a special bond that would transcend things like blood. It's that bond that starts showing some cats they can be close to others who aren't their blood-kin. Cloud is treated a little more like Firekin.
Both Sorrelkit and Rainkit have epilepsy, though Sorrel's is made worse by Darkstripe. Rainkit's seizures are really annoying to him, especially of they happen while he's trying to play with his brother and sister. They're not common but he makes a big fuss when his absent seizure makes him unaware that Sorrelkit was about to find his hiding spot. Sorrelkit isn't bothered when she has one, the cheerful kid never seems to let things get to her.
The first leader ceremony seen is Firestar's. We see Nightstar's failed ceremony and, after The Darkest Hour, we see Tigerstar's in his own book, Tigerclaw's Fury.
Leopardstar is referenced to have been named for the strength of Leopardclan, and her own crimes are much more subtly pronounced then Tigerstar's.
Fireheart's explicitly favorite thing to learn is Clan History, especially the Mythical Clans. He becomes close with Willowpelt through this, as she is the Historian of Thunderclan.
