If you have the money get a Baby Death (Century Optics). But I don't have the money and assuming you don't I would get something from Opteka. The .3x and .43x fisheyes are fine to start with.
Wideangle does what you said it does, makes the image wider. What you might want to understand is its the opposite of telephoto (zooming). 1x is where your camera is when it zoomed out all the way with no lense attachments. .7x is close to 1x so the view your camera can see doesn't stretch a ton, so there won't be as much distortion. If you want to see alot more or want the fisheye effect then .3x is much wider, but has bending in the picture (which for lines and other shots you probably want). For fisheye lenses you shoot close ups or follow the rider. NEVER shoot with an extreme wideangle or fisheye from a distance. You'll barely be able to see the rider and it looks crappy.
Also, a word of advice: Once you get the fisheye/wideangle, take it off once and awhile.