I use an xbox 360 controller on pc, and the throttle button (back right thingy) is not binary, there is throttle control. I’d check that your gamepad is able to do it, I don’t think the old console generation type controllers could do it.
I don’t know about how people steer so accurately with gamepads, I struggle but I have gotten better over time, maybe it’s practice. I’m now just able to compete against professional AI with no traction control or abs in F1 2011, using Mercedes. Have heard F1 2012 changed things around though, can’t offer advice on that.
I think you can play with the deadzone and linearity settings for controllers, that might make it easier to steer. I honestly haven’t changed them and just tried to adapt to the default, but I might give it a try now.