in the battle that took place as rusty (fire star) joins thunder clan, red tail killed oak heart. tiger claw tells raven paw to go and get help for red tails injuries, but instead raven paw hangs back. he stayed just long enough to see tiger claw kill red tail. tiger claw hoped he would be chosen as the new deputy. if you want to know the rest, read "into the wild" which is the first book in the original warriors series
If you mean in publishing order, then Redtail in Into the Wild is the first cat to die. Chronologically, I have no idea.
In "Fire and Ice," the cats that die are Redtail, a ThunderClan deputy who is killed by Tigerclaw, and Whiteclaw, a RiverClan warrior who dies in a battle with ThunderClan. Additionally, Frostfur's kits are killed by ShadowClan warriors during a raid on ThunderClan camp.
Just wherever.
no
yes in Into the WildYeah. In the first book of the warrior series Rusty (Firepaw's pet name, he hasn't gotten his clan name yet) enters the camp of thunderclan. A warrior runs into the camp in distress telling the clan about a battle that was happening at the time. Later on, they find that Redtail (The thunderclan deputy) was killed by an "Enemy from an other clan" but it was really tigerclaw in hopes that if he killed redtail that bluestar (The Thunderclan leader) would pick him as the next deputy.
*!SPOILER ALERT!* No. She later becomes a warrior. Her warrior name is Ivypool.
The clan where warrior cats go when they die is called StarClan. It is a group of the spirits of deceased warriors, leaders, and medicine cats who watch over and guide the living cats of the forest.
When the cats battle.
So far she hasn't died yet.
One of them is Tallstar. Another one is Pinestar.
yes, he was slayed by Tigerstar.
Yes, he did die. I'm looking on the Warrior Cats Wiki, and it doesn't say how.