Well if you look at the two screenshots shown above it's pretty obvious that the configuration is fairly different. Son in that sense, yes, the mapping is the same, but different.

I'm not too sure about riving wheels & foot peddles though. I would assume that they are about the same. Which would lead me to my questions of how a game would manage a wheel device that turned all the way around. Or are they even able to do as much. Sorry, I've never used one myself.

I'd be interested in seeing a technical spec of a wheel though. Specifically how it's axis is oriented.

As far as libraries go... in the case of DirectInput(or any other API), it's really just reading states, which will probably be the easiest part of your game engine. The slightly trickier part is designing a layer on top of that to read information that the API gathered and turn it into something useful for your game. It's the same with SDL or any other API that will read the states of your game devices for you.