9) Why has DC been reconsidered after more than a century of AC domination?
The main reason that AC won the War of Currents more than a century ago is that AC is more cost effective. DC installations are very expensive and a DC substation requires more equipment than an AC substation would require due to the conversion process.
Nowadays, with the price of electronic devices dropping, using DC to deliver power has been reconsidered. Since many end use devices operate with DC and renewables use DC power (PV, BESS, wind), DC microgrids are proposed by researchers around the world as a viable alternative to usual AC systems.