Ok, at least in nightly r793 here, old and modern runways a) look different, b) are available in a different time, c) have different speeds, d) different costs and e) different weight limits (in case these ever get used). So I really don't know what your problem is there... What more difference do you want?
And #12, 13 and 14 are coded as (minimum level) extension buildings - and they work as such (unfortunately)* but i repeat: they are mainly just for the looks. So it's up to you if you use them or not. They are no more plane stops (or have any moren hidden functions) than the radar antenna or the tower or the terminal buildings among which they are placed on the menu.
*) I'd rather have them without function at all (but I want them as player buildings, not as curiosities, so that's the best that could be done so far)