I have to push the horn very hard to get it to work. Is there a switch underneath the airbag I can replace to remedy this?
How do I go about replacing it? How do I get the air bag out of the center of the wheel to replace what needs to be replaced?

First disable the airbag system before you try ANYTHING <disconnecting batt for a while, or even pulling the airbag fuse for a while too>. Then there should be 4 bolts on the back side of the steering wheel, which should free up the airbag when they are removed. Beyond that, the gearheads would know more than I do.