Hi rancum,
I'll try to help you with this, but remember I've only been studying Japanese for two years, so I can't say for sure my translations are correct
For time timedifference you can use the word: 時差
So you could say "The time difference is two hours": 時差は2時間です。
As for your expressions:
"My time is 2 hours behind yours"
こちらの時間がそちらの時間に2時間遅れている。 i used kochira and sochira here instead of you and me. As in the time here and the time there.
I don't recall how to say correctly that my time is 2 hours ahead, but you could switch the times to say the other person's time is 2 hours behind on yours.
"I will call you at [2pm] of [Japan] Time"
午後2時日本時間に電話する。 / 日本時間午後2時に電話する。 I don't know if this is the correct way and order to say it but I'm sure.
Hope this helps.