Opentype fonts

Is there an open source FO processor that can handle opentype fonts?  I've tried changing fonts with FOP (which I use now), but I can't get it to work, even with truetype fonts.  I'm currently using Saxon65, XSLT 1.0 and FOP 0.94.  I have also noticed that FOP doesn't support double sided printing.  Is this true?  Or is there a parameter that needs to be set for this to work?

Thanks!

Lillian Sullam