No. the total power dissiapted to an element is not the sum of the powers dissipated by the individual sources. You can find voltage or current using superposition and then calculate overall power, though
Superposition can be used to find the total current when it is in the time domain. Using that current, you can then find voltage across or power absorbed by a resistor.
In the phasor domain, superposition can be used to find the total power by adding together the power from each source. The currents can NOT be added in the phasor domain if they have different phases (superposition does NOT apply if the voltage or power sources are out of phase). However, using the individual currents from each of the sources it is possible to find the power resulting from each of the individual sources, and the sum of the individual powers is the total power.
No, because power is proportional to voltage squared or current squared. If you accept that superposition works for these, try to see why it wouldn't work for another value that has a squared relationship with them.