Hi,
RISC, CISC:
* In the past RISC prcessors had low transistor count, and thus only maybe 32 instructions. Thus parsing an instruction was not that complex and was fast. But for example a "multiplication" needed a lot of instructions.
* Nowadays even RISC processors may have several hundreds of instructions. Even RISC processors now have a "multiplication" instruction.
Thus the difference is not that big than in the past.
ARM power consumption vs x86 power consumption: I just did an internet search about this topic. There are more than enough hits. --> Read through them.
Klaus