Will an imported head-unit work in a USDM vehicle? Options

[Zimluura]

i'm lookintg at getting a new head unit. the alpine one i have has too many green lights on it (they're surface mount LEDs and allot fo them so soldering new stuff it looks really hard).

here's what i'm looking at getting
http://www.yakumo.com/produkte/index.php?pid=1&ag=Autoradio

i found a place in the uk that said they'd ship it to me if i wanted but they were a little curious to know if it'd work in a us car.

so here are my questions
1) i assumed the differences in cars were based on the manufacturer (toyota) and never regional, and that the wiring harness would hook any aftermarket car stereo up to vehicles of that manufacturer. is this a correct assumption?

2) will i need any other euipment to install it in my car, if i already have an aftermarket head-unit in there? should i get another toyota wire harness?

thanks in advance