Since no one with first hand knowledge has chimed in - here are some old threads that deal with UW. My daughter joined two years ago and is still very happy. I know she has had upper classmen receive bids from her GLO, but I don't know any of the details (friends already in chapter, transfer?) and I never got the impression that it was that unusual for
some upper classmen to received bids. I don't believe they have a separate upper class quota.
Recruitment Stories
Some have happy endings; some don't. Obviously the 2007 stories are more accurate as to the process. I think the 2003 girl got to see all her invites and choose which no longer happens.
First from 2003
http://www.greekchat.com/gcforums/showthread.php?t=38808
then from 2006
http://www.greekchat.com/gcforums/showthread.php?t=77659
three from 2007
http://www.greekchat.com/gcforums/showthread.php?t=89800
http://www.greekchat.com/gcforums/showthread.php?t=89819
http://www.greekchat.com/gcforums/showthread.php?t=90189
My advice is to go into those first two days with an open mind and not to set your heart on just a few groups. Some groups must make heavy cuts after those first parties and you don't want to be disappointed about who you don't get back, instead be excited by who invites you back.
You do have to rank them, so I suggest as you walk out think - Did I like them, think they were OK, or need to meet them again to decide? That way if you rank - need to meet again at the bottom and are invited back you are already thinking that you need to meet them again, not the chapters I didn't like invited me back. Because as everyone here on GC will tell you, your opinions can change from day to day.
I suspect AXOMOM is correct about the bids. Quota additions have been up to ten girls in the past few years. But, I haven't seen any thing in writing or be told that they have guaranteed bids.
In the past, they gave you a T-shirt to wear to the first round. As it gets closer to recruitment, panhellenic usually puts pictures of suggested outfits on the website with a recruitment guide. Keep checking the website for the guide.
Good luck, it is definitely worth the effort and UW has beautiful houses! They should hold a Panhellenic fundraiser giving tours. I know I would fly up to see them all.