almost!
seigel invented superman and shuster drew him. shuster came up with the newpaper backstory as he had worked as a little kid for the toronto newpaper a bit and obviously 'the daily planet' is a mix of toronto newspaper monikers.
the old toronto star building was not the inspiration for daily planet hq building. for one thing, shuster moved to cleveland before it was even built, and for another the newspaper building was often depicted differently. in fact the old deco att ohio bldg tower in cleveland more likely played a part, but again the news building is often depicted differently and was not given much thought early on, so its really an amalgamation of buildings typical of the era.
as for toronto being metropolis? oh please. toronto was a bump in the road back then and peaking cleveland was the metropolis initially, if anywhere. hell toronto didn't even pass cleveland metro until the late 1960s. hard to believe nowadays, but just goes to show you toronto's explosive growth since then (and ne ohio's stagnation, unfortunately).
anyway, the duo literally came up with superman imagining him flying around the cleveland terminal tower, so if anything that is actually the key single structure in superman history by their own words and without question.
of course what is also for sure the case is that nyc quickly became the true metropolis when they went out there and made comic book history.
and that's about it for superman. now about howard the duck ... !
