The flash gallery tutorial

hi there i got a question about the flash gallery tutorial you got on this site.
after i have succesfuly compleeted it and added some things to it my self i got 2 problems left i cant seem to fix. How can i make sure the movieclip centers all the photo’s i add using the xml file and is there a way i can make em clickable so that they link to a larger photo of the photo iam currently viewing?

thx for reading and your help on this:).
and great tutorial it helpt me understand even more about the connection of flash and xml