1) If you want an Ogre mesh, find the mesh file in the track file. If it is not a .xml file, then put it through the Ogre xml converter by dragging the mesh file and dropping it on top of the converter. (you can find this in your RoR .37 folder, not sure if newer versions have it.). You will need Ogre importers/exporters. You can find downloads for those here:
2) You can find cars, buses, vans, etc under the "Scrapyard" section of the downloads section. There are other models out there that you can't download from the site, but you can get these by asking around.
3) Yes, although make the racing version first, then save it. Then use the racing version to make freestyle, then save that as a separate track. Put all the files together in a folder, then upload.
This was a kind of brief summary of everything you asked about; you can find more in-depth tutorials on here as well. Most track makers on the site will not mind helping new track makers with finding models, techniques, baking, etc. Track making can be a bit frustrating at first, so just hang with it. Blender can also take a while to get used to, but with enough patience you'll be making good tracks in time.
Threads like these should also go under the "Help and Support" section.