Seems everyone else has covered your main questions so I thought I'd add a few things from an Aussie who's visited the US a few times:

• our Coke is more like Mexican Coke
• our chocolate is different
• our licorice is better and plentiful (try the bullets)
• we don't have orange chicken
• we have chicken sushi though (it's cooked, don't worry)
• mint slice biscuits > thin mints
• there aren't as many flavour varieties for drinks/snacks here, also our chip packets are coloured different
• it will get hot in summer, and I mean hot, so make sure you have air con or something where you're moving to, it can get over 100°F