wifi networking

I am new to wifi networking, well networking period.

Say for example I have a 3g wireless internet provider and I am connected through USB. I am wanting to play PS3 online. Is there a way to share my connection since my laptop and PS3 both have wifi built in?

Same question but this time I would be connecting my laptop to a city wifi hotspot. Obviously using wifi.
Since I would be connecting my laptop using wifi, would I be able to share my connection with PS3 via wifi as well? Laptop to PS3 eventhough I am already connected Laptop to wifi hotspot.????

I had broadband before with the router setup, I have relocated and ISP's are limited. Just trying to kill two birds with one stone.

Any help would be greatly appreciated, thank you for your time.