Gas prices

Why is it that 7-Eleven sells unleaded for $2.49 per gallon, and Chevron, right across the street, sells it for $2.61?

Someone please explain to me three things:

1). Who sets the prices?

2). Why gas prices rise immediately when oil prices rise, yet lag behind when oil prices fall?

3). Why Americans passively accept this?

Are we all so relieved that prices have dropped below $4 per gallon that we silently rejoice in our good fortune? Do we thank the omnipotent oil executives for sacrificing profits to benefit the masses?

Interestingly enough, the Chevron had several customers buying gas, and 7-Eleven was almost empty. Apparently 12 cents per gallon doesn't matter to these people, but name-brand does.

Fascinating.