Where did Ehud live?

Eglon's assistants returned when too much time had elapsed and found the doors locked. Assuming that he was relieving himself, they waited "to the point of embarrassment" before unlocking the door and finding their king dead. Ehud escaped to the town of Seraiah in Ephraim.

Were benjamites left-handed?

In addition to the left-handed Benjamite Ehud, Judges 20:16 refers to 700 Benjamites who could use the sling with great accuracy ("Every one could sling a stone at a hair and not miss") and all were left-handed.