I have noticed a greenish substance on top of my furnace around the fittings and pipes. If you are looking at the front of the unit right on top. Is it anything to worry about?
You can get PVC pipe with steel pipe threads, see ACE hardware.
It depends on whether it can collect money - usually it can't. Fares are sold in proper POS (usually vending machines, rarely in manned kiosks) in dedicated areas close to access control devices (turnstiles or similar). The reason is to speed up access and enable sale of sophisticated special tickets (dailies, weeklies, monthlies, senior, student etc). The effective ticket validation takes place at access points (turnstile level) and it must be very fast and reliable. Part of a transit system sustainability depends on this.
