Electronic – Smallest touch that can be detected on smartphone touchscreens

so that means that I should be able to interact with it as long as I can bring a small current to the screen where I want to touch.

No. You don't "bring" current to the device. These devices measure capacitance, not current or voltage. The additional capacitance thru your body back to ambient or circuit ground is detected by looking at how the capacitive pad responds to some specifically chosen signals.

I expect the high-resolution display to use slightly more, but roughly the same amount of power as the lower-resolution display.

Most of the power consumed by the display in a tablet like this goes to two primary components: the backlight and the LCD.

Typically the backlight consumes very roughly 75% of the energy going to the screen. Most tablets like this one have a CCFL tube backlight; some of them have a "white LED" backlight. It doesn't change the answer for this question -- given either kind of backlight, that backlight will consume exactly the same amount of power no matter what LCD is placed in front of it. Turning the "brightness" down can save a significant amount of energy.

As you probably already know, the "liquid crystal display" (LCD) such as the ones in the tablets you mention act as shutters -- they either let the light through, or they block the light, or something in-between. They typically consume the other 25% or so of the energy going to the screen.

Some of that energy goes to keeping the liquid crystals "open" (or "closed"). A cluster of 4 pixels requires exactly the same power to keep the liquid crystals "open" (or to keep "closed") as a single pixel 4 times the size.

Some of that energy is lost due to parasitic capacitance of the INO transparent "wires" on the screen. The total row capacitance and the total column capacitance is about the same for the two screens, so the amount of energy required to update a row (charging and discharging every column line across the entire screen) is the same. However, the higher-resolution screen has more rows to update, so assuming the same full-screen update rate, it requires more power.

As a side effect of the screen having a higher resultion, the CPU and the CPU-to-display bus will have to do a little more work dealing with more pixels.

So the things that use up the most power use exactly the same amount of power no matter what the resolution. There are a few things that require more energy for the higher-resolution screen. So I expect the high-resolution display to use slightly more, but roughly the same amount of power as the lower-resolution display.