The DRAM sticks in a PC have nothing to do with the SRAM in a tablet. The SRAM idle power consumption is almost purely leakage, and will be proportional to the number of gates - thus doubling capacity will double power consumption. Active power is unlikely to be significantly affected by doubling the memory, however.
As far as faster CPUs, even on the same process a CPU is synthesized for a target speed. If you want a slower CPU, the synthesis creates smaller (lower-power) transistors, and uses fewer buffers and/or synchronization stages. If you run a CPU synthesized to run at 2GHz at a 1 GHz clock rate, it'll take significantly more power than the same CPU, in the same process, synthesized to run at 1 GHz with a 1 GHz clock rate. At idle, the CPU synthesized for the higher clock rate will have higher leakage.
So, both of your statements are incorrect.