I agree with all those points, I've wondered why Volvo put them where they did as well. Maybe in Sweden things don't get so hot under the hood!

They did try to get some air going into the box that contains those boards. See that plastic duct that runs from the ECU box to the front? That picks up cool air coming in through the grill, sort of a ram air cooling system for the ECU. There's even a little filter inside that duct that I think is supposed to be changed every now and then. How well this thing works is anyones guess, I guess you could put thermocouples and sensors in there and monitor it if you were really bored and needed something to do.