Here is my answer:

1. The Grizzly Bears. We would wear bone jewelry made from both animal and human remains.
2. I would tell my tribe I'm going on a "spiritual journey" and leave for a short time, picking the strongest to lead in my absence. When I return, I shall proclaim I heard a voice from the wise spirits, telling me how to govern the tribe so we may be victorious. The women must become docile, preparing food and being used for procreation while the men did the hunting and fighting. Any women of at least speaking and walking age must agree to any sexual desires or commands of the men. Growing up, men will be taught how to fight and catch food, while women learn to cook and how to please the males. Those who disobey must be killed and used for food to sustain the rest of the obedient tribe. "So is the wisdom of the wise and ageless spirits", I would say.
3. We would use camouflage and attack other tribes in the dead of night, making sure to attack from all sides, from high ground if possible. If nothing needs to be taken from their camp, we would use fire to destroy the buildings and the surrounding area before fighting, and then use fire against the people. Our tribe would use javelins and bows to attack from a distance first, then charge in with spears. Those who fight back would be killed outright, their bodies saved for food if possible. The weak survivors would be captured and taken back to be used as food or slaves.
Bonus Question: Solar-powered walkway lights, a bucket, a few torches, a small axe, a small shovel, a blade sharpener, and a few-printed out pages of guides on outdoor survival, constructing rudimentary weapons, fighting tactics, and optimal parts of the body for cannibalism.