Bring 4 cups water, rice, and salt to boil in heavy medium saucepan over high heat, stirring occasionally. Reduce heat to low; cover and cook until rice is tender and water is absorbed, about 20 minutes. Uncover saucepan and cook rice over very low heat until dry, about 5 minutes. Transfer rice to large bowl and cool to room temperature.
Whisk orange juice and next 5 ingredients in small bowl to blend.
Add halved tomatoes, cucumbers, green onions, mint, and feta to rice in large bowl. Add dressing; toss to blend. (Can be made 8 hours ahead; cover and refrigerate. Bring to room temperature and toss before serving.)
