Hope someone can help with these upgrade questions.

1. As a Gold elite, can I upgrade a passenger after I've boarded the plane? I'm thinking a potential client might be on the same plane that I might be on tonite and I'm pretty sure he'll be back in coach.

2. Can I use my miles to upgrade other passengers tickets on some upcoming flights?
These are current clients and I'll like to get some good "mileage" out of my miles. If so, what is the cost in miles?