If one rides systems around the world, there is a wide range what you maybe sitting on. Wood, Plastic, Fiber, Fiber padding, Foam and so on are what you can find on any vehicle and it depends on the system and what they are willing to pay for them. The PCC's and the H4 had form seats, but wouldn't last long on today cars due to vandalizing that take place today. You can find cut fiber seats today on any type of vehicle for TTC.
Depending on what TTC wants to save as heritage cars and will use them for charters, they will carry a stockpile of poles until the cars are converted to Pans.
As for overhead, most lines straight section are 75-100% converted, but not all intersections. Some straight lines may have areas where it a hit and miss where either a short or long is missing between sections. Everything from Long Branch Loop to Parkside Dr is 100% converted for 501 in the west and 100% done east of Parliament..509, 510, 511, 512 is completely done, but no idea why 512 is being shutdown for a number of week east of St Clair W Station to fix it. Starting later this year with luck, cars will be able to leave the Barns with pans up for the current pan routes.