How to activate gophone from Abroad

Hello

I am a resident of Japan and I have scredule for short time visit on educational and research purpose to US. I buaght a AT&T micro SIM and want to activate and select plan while I am in Japan. So that I can use it just after arriving LA and also provide my number to some of my colleagues.

My Questions are,

1) Can I activate and sign up while I am in Japan?

2) Can I use my Hotel address to activate the SIM card?

Best regards

Rito