There are many resources
We are all students in the Koi world.  It seems that you find out some bit of information that leads to a lot more questions than may be answered by what you find in print or on the web.  (Beware...you will find the best and worst information on the internet...)  Here are some web forums where you can pose a question and get answers from many experienced people:

Koiphen Forum

Koi-Bito Forum

KoiShack Forum

Nishikigoi International Forum

Koi Club Information
There are several local Koi Clubs that we can recommend:

ZNA NorCal

Santa Clara Koi & Water Garden Club

Camellia Koi Club (Sacramento area)

San Francisco Bay Area Koi Club

     for those not in the SF Bay Area:

Assoc. Koi Clubs of America (all USA)