A:AnswerIn the grand scheme of things it really doesn't matter. There should be zero performance hit. If you choose to upgrade, you'll probably have to replace both no matter what. I wouldn't buy extra RAM through Dell anyway.
A:AnswerThe power unit is 100-240V.
I tried to buy a white one 1 month ago but Best Buy only had black units then.
I think the white model is cool, but keep in mind that it's white only outside, all are black inside.