Welcome to the forums!
If you're new to the API, you can find a lot of free beginner resources at my site (see link below). If you want to know specifically what API interfaces to use, you'll want to look at IMassProperty. If you want to determine whether a part is cylindrical, you would need to look at methods like ISurface::IsCylinder or ISurface::IsPlane. As for orientation, you could get the normal values of faces (IFace2::Normal) or you could get the transform data using IMathTransform. I will warn you, though, using component transforms with the API can be tough if you're a novice API user. We have a premium tutorial that covers component transforms, FYI. See lesson 5.3.