No, he doesn't.
No, as far as we know Longtail did not have a mate, and Mousefur never had kits.
no yes he ambushed him mousefur and thornpaw and killed runningwind.
Runningwind was killed by a pack of dogs during a battle in the book series Warriors by Erin Hunter.
Tigerstar killed Runningwind as part of a plan to weaken ThunderClan and provoke conflict between the clans. He wanted to assert his dominance and show his power as a threat to those who opposed him. Runningwind's death was a deliberate act of violence to further Tigerstar's own ambitions and control over the forest.
No, he doesn't have any kits.
No, he was an innocent warrior.
yes they are brother and sister
Dovewing and Foxleap do not have kits together, nor become mates.
yes. He is killed by Tigerclaw and his band of rouges.
No
really his family is unknown his father is unknown but his mother is one-eye (white-eye) and his sister is mousefur Edit: Runningwind's only sibling is Mousefur. His mother is White-eye (One-eye) and his father is Sparrowpelt (Halftail), neither of which parented another litter.
No, Spottedleaf did not have any kits in the Warriors series.