Most Toronto area homes built in the 1950's-60's will have Romex-type copper wiring cables, but may not have a ground wire - those built after 1965 will for sure. Late 1960's and 1970's houses may have aluminum wiring. Houses with aluminum wiring can have a plethora of issues, reanging from mixed wiring and incompatible devices (switches, outlets, and breaker panels), to corroded mixed connections & arcing.
Plumbing will typically be copper hot/cold iside supply, and copper or cast iron DWV. The street cold water supply will likely be galvanized steel pipe unless it has been replaced - if the house has low water pressure or rust coloured tap water, then you likely have steel coming in from the street, otherwise it's likely copper.
It's unlikely that any 1950's era home will have insulated walls unless they were gutted and insulated later. Wall insulation didn't become commonplace until the 1960's. What was done to many 1960's and earlier brick-wall homes in the 1970's was the injection of urea-formaldehyde foam (UFFI) into the walls from the outside into the 1"-2" gap between the plaster interior walls and the inside surface of the brick (presuming brick construction).
There were several problems with UFFI:
1) as it cures it off-gasses formaldehyde - which isn't good for you
2) it can crumble into powder after a number of years
3) it reacts with water/moisture
The first problem precipitated a furry of crap and panic in that nobody wanted to buy a UFFI insulated house unless it was stripped out of the walls by gutting the house. Sellers were forced to sign UFFI clauses when selling homes. You couldn't get a CMHC insured mortgage back then if the house still had UFFI in it.
As it turns out, the amount of formaldehyde leaching into homes as a result of UFFI was less than that given off by brand new nylon or polypropylene based broadloom (at least the way the carpets were made in the late 1970's and early 1980's). CMHC later relented in the face of scientific studies confirming this, and the no UFFI issue legally disappeared, but dumb-ass real estate agents still shove contracts with the UFFI exclusion clause into deals.
So for the UFFI issues, install an HRV and live with it if the house has it (look for patched circular holes in the exterior walls - this would be where the UFFI was injected into the wall cavities).