Hopefully an expert in CAPD will chime in, and seeking the advice of experts is almost always a good thing.  There is an excellent resource in my area on CAPD, Judith Paton.  Google search her and you'll find her easily.  If you live in the San Francisco bay area, seeking her out for an eval and consultation would be a good idea.
 
There are a lot of things, in my personal experience with CAPD, that can help. Some of it concerns expectations and coping behaviors.  For a student, if you are facing a foreign language requirement in school, seek an IEP that acknowledges the CAPD and make accommodations for it.  Don't try to satisfy the foreign language requirement with a language that is highly distinct from your son's native language - for English speakers, I think Spanish or German would be better than Japanese.  An all-verbal course (like the popular language CDs) probably won't work very well.  One therapist told me recently that she often gets college students coming to her unable to pass a foreign language requirement, only to be tested positive for CAPD, and this is their first diagnosis.  You are fortunate to have found this early.
 
Other things I've learned over the years are
 
* Write out instructions for him; it is likely that he can understand written instructions better than verbal (you probably already know this).
 
* Make sure he sits in the front of the class.  If the teacher seats students alphabetically, seek an accommodation that allows him  a front row seat.
 
* Speak directly toward him and make sure the teachers know this, too.  "Point your mouth towards him" is something to remember.
 
* Make sure he can type; get him into a typing course early if not.  CAPD's often are far better in written communication than in verbal.
 
* Speak clearly and distinctly and precisely in complete sentences and thoughts.  Remember that CAPD's can have trouble sorting out sounds into words, so the ... more ... distinct ... your ... words ... are ... and ... separated ... from ... each ... other the better he will understand you.  Some CAPDs, even when they hear all of the words distinctly, conjure up a dozen interpretations of what was said and aren't able to pick the one that is best in the context.  Also, finish your sentences, stop, and give him time to process.
 
* Create a quiet environment for him to study and do homework in.  It can be difficult for CAPDs to tune anything out.  Earplugs might help.
 
More things will probably come to me in the next day and if so, I'll follow up with more.

Students with APD need a very multisensory approach to learning.  They often struggle in the classroom because teachers rely heavily on lecture and talking.  For a student with APD, this is not their learning modality.  In order to tap into their visual and kinesthetic modalities every lesson needs to be a see it, hear it, say it and move with it.
 
Although there are hundreds of tips and strategies I can offer you, I'll give you a couple to start with.  
 
Have your child "talk out loud" while studying.  So for example, after he reads a paragraph, have him stop and summarize the paragraph out loud.  Then write down a one sentence summary.  Continue this way until the chapter is over.  Then have your son go back to the beginning of his notes and read them all out loud.  Have him summarize the entire chapter to you out loud.  Trust me, he'll have it.
 
When studying a chapter for a test - do not do the entire chapter at one time.  On Monday read page 1.  On Tuesday review page 1 and read page 2.  On Wednesday review page 1 and 2 and then read page 3.  On Thursday review pages 1-3 and read page 4.  Continue this way also implementing the multisensory strategies I mentioned.  It is important to use this technique with everything.  Often children with APD struggle with short term memory deficits.  Your son must never "cram" for a test or the information won't stick.  
 
 A great book to read is "When the brain doesn't hear."  
 
Good Luck and stay positive and motivating!
Here is a link to some info on APD: