Yes, you can have the valvetrain off 180°, making the Distributor off 180° and the engine will run just fine, but now your SYNC signal is off 180°. Some will say the SYNC signal will correct itself every time you START and RUN your engine if that what you want.
Yes. TDC has two meanings. With timing you're looking for TDC during the Compression↑TDC↓Power stroke.