Yes the Welcome sign is great.
Also to add about "keeping the racetrack in shape".... I am not too sure any racing series would ever allow racing on such a cracked up and broken track
Possibly, if you want to make an old looking track... create cracks in the main tarmac (all over the place), but on the edge, maybe give a sign of cracking, but also overgrowth of grass and dirt, and possibly the lines on the tarmac being worn or unpainted in some areas (think you might have done that).
If you look are REALLY old surfaces, you will also notice that they tend to patch it up with some kind of concrete or something. I think Nuburgring even has several patches (or a lot).
http://www.obra.org/track/images/history/old_track.jpg (bicycle track, but same thing)
But look at this picture... the edge of the track is what I've seen most tracks do... They usually pave a new little edge of concrete to repair such things, all around the track. This isn't just for the curbing in most cases:
http://www.motoringpicturelibr ... docs/hi-mpl340001623c.jpg
Also, for some of the metal guardrailings, I would personally paint them a very "classic" mustard yellow with black or white striping. EDIT: Hmmm this springs to mind:
here
Maybe even give it classic haybale style walls somewhere:
http://www.motoringpicturelibrary.com/docs/371-mplc.jpg
But you get the picture... do what you think is best