DVB-T Terrestrial (Over the air) broadcast from a tower using COFDM DVB-C Cable using usually 64QAM, 128QAM or 256QAM DVB-S Satellite using QPSK
Yes. The ERP in DVB-T is usually much less than in PAL. However, it appears that the power for analog is measured at the synch tip, while for digital systems, this is some kind of average power. As with all multicarrier systems, there is the peak to average ratio problem.
Paul