Dress Robes and a question about Sirius/Lupin

[grace701]

No: HPFGUIDX 53677

My first question is can anyone direct me to where I can see what 
dress robes look like?  I have never seen one before and I find it 
hard to imagine what the Trio, and everyone else, are wearing for the 
Yule Ball.  I automatically switch to suits and dresses.  Plus, I 
just can't picture guys wearing robes, if that's what it actually 
looks like.


Now my question about Sirius and Lupin.  My neighbor has my PoA book 
(and I have a feeling I'm never going to get it back), if I did have 
it I wouldn't bother to ask.  Anyhow, how does Sirius know exactly 
where to find Harry at the Dursley's on Privet Drive?  And why hasn't 
Lupin tried to contact Harry once he's reached Hogwarts?  


Greicy