Feathertail, Runningnose, Hawkfrost, Sootfur, Cinderpelt(reincarnated), Molekit, Ferntail's kits except for Birchfall, an apprentice that fell during the journey, Tallstar, mudclaw, shrewpaw, frostfur speckletail dappletail and other elders stay behind, mudfur, and those are just some that I can remember.
Leopardstar dies in Fading Echoes
Yes, Foxleap dies in the Warriors series. He dies in the battle against the Dark Forest.
In the book "Warriors: Sunrise" from the Warriors series by Erin Hunter, the character who dies is Bright Stream, who dies defending her kit, White Tail, from an attack by a shadowed figure.
In the book "Sunrise" of the Warriors series, Hollyleaf dies after being trapped in a tunnel collapse. She sacrifices herself to save Ivypool and Dovepaw.
As far as the series has gone, Brackenfur hasn't died yet.
Yes, Sharptooth dies in the Warriors series. He dies after falling into a gorge during a battle with the Clans.
Heavystep, a ThunderClan warrior in the Warriors series, dies twice in different books: once in a battle against ShadowClan in the original series and then again in a battle against the badgers in the later series.
When the leader of a clan dies in the Warriors book series, the deputy usually takes over as the new leader. The deputy is the cat chosen by the leader who is next in line to lead the clan.
Yes, she dies in The Forest of Secrets, which is the first book of the first series, bearing Graystripe's kits.
Scourge dies in the 6th book of the Original Arc 'The Darkest Hour'.
Darkstripe dies before he can have a mate in book 6 the darkest hour. He died in the battle of Bloodclan killed by Graystripe
Sandstorm dies in the Warriors series in the book "The Last Hope" during the battle against the Dark Forest. She sacrifices herself to save Firestar from a fatal attack.