Catholic in a Synagogue

OK, I am trying to look into the faiths of some other relgions. I am a catholic and I am making plans to attend various different christain denomination's services and even try to go out of the christan relm. Well friday night I am planning to go to a Synagogue and I have done a quick search on what to expect and how I should act. Now I have never been to any servicies outside the catholic church and thats why I am doing this... and also because it will do me good considering im alomst a seminarain....

So what sould I expect?

Anything that I MUST KNOW?

What can I do so I am not disrespectful?

How should I dress?