Worrisome Plackets

This pattern has been bouncing around in my pattern box for two or more years.  Every time I go to cut them out, I chicken out.  What's been stopping me?  Plackets, or the fly.  I just don't get them.

 Finally, I gathered up the courage and bought enough yardage to make 4 pairs.  So far two are done.  I'm not a huge fan of flat felled seams either but they do look nice.  The red pair was my first and I used flat felled seams.  The second I cheated and used my serger to finish seams.  For the next two I'll slow down and do the flat felled seams.  They do make a nicer pair of shorts.