Since NS still uses the Backside Route of the Toledo Terminal between Gould and Vulcan, it is highly unlikely that a trail will ever be found south of Vulcan. It would have to go alongside the used ROW and cross the NS Chicago main at Nasby. Personally, I don't see the need or any demand for a trail along this stretch.
I have been to several presentations held by city, metropark, and Rails to Trails officials and have basically come away with the conclusion that a trail would work from around Laskey (Bowman Park area) southward to Ottawa Park, where the Backside Trail (as it would be called) would hook up with the already-existing park trail system, and then connect to the south with the University Parks Trail (at Vulcan), which runs west to Wildwood, its trail network, and to King Road. Of course, as we all know, nothing happens quickly in this town so we'll just have to continue to wait.
As for train frequency and times, I can't help you too much because I'm unfamiliar with exactly what runs east/west thru Gould but I know the Andersons and John's Manville to the west do pretty good business. The terminal only gets a local once every other day I think but all trains thru Gould are either "locals" or "yard jobs", leading me to believe that most would run during the daylight. At any rate, I doubt many of your future neighbors near Gould lose much sleep due to trains. If you're concerned though, ask them.
Best of Luck. (let the forum know what you see pass your house)