二零一零年十二月二十号的问题

Questions are a little short on the ground today as 圣诞节 is begining to intrude on my study time.  I have some though and think that they may take a while to talk through.

1) What is a Dishwashing machine called in china.  I have two guesses 洗碗机 and 电洗碗.

2) I just encountered the character 被 I read about it in a grammar book but am not convinced I understand it.  Can you help me with some examples..?

3) 气温 is air temprature.  Should I say 今天气温是零下六度 or is 今天是零下六度 enough...