What's the differenct bewteen "on" and "at"? Should I write "The hospital is on the Hospital Street." or "The hospital is at the Hospital Street."
Yes, we would say "on" for that.
(It's at the corner of Hospital Street and Spruce Avenue.)
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.