Excellent, Daisy! I am so glad you finally found your mixte... and in a large 57cm size!! They're so hard to come by.

Tires: 27" x 1 1/4" - I use Vittoria Zaffiro and love'em! Cushy, smooth ride, no punctures and inexpensive.

Fenders: I also had issues fitting fenders in my Nishiki Mixte. I used flat Woody fenders which fit in the back but not up front. If fenders are a must for you (and you do encounter that that they don't fit), a solution is to change the front wheel to 700c and use skinny 23-25mm tires. That's what I did. It wasn't necessary to change brake calipers up front. You end up with mismatched wheels and tires, but no one will notice. Another idea is to use shorty fenders up front. They just cover the back part of the wheel. Some people don't like them aesthetically.

Stem - A nice quill stem that allows you to play around with height and angle is this one. It comes in shiny chrome which looks nice:
http://www.jensonusa.com/store/produ...uill+Stem.aspx

Yeah.. don't forget to take pictures of "before" and "after". Sometimes I forget and regret later. It's always nice to look back and take pride in your work.