1: Killed all 5
2: approx 280 hours in that world
3: Spear - 44
4: Bow - 20
5: Running - 63. Wood cutting - 30. Pickaxes - 36
6: I'd say it's been a balanced game between exploring, building and grinding.
7: No tricks, cheats or mods.

I've played approx half of the time in this world in co-op. Might affect progression in some ways.