[Greenbuilding] Mold questions

[Jefro]

We live in northern coastal California where mold is a special problem.  
Relative humidity averages something like 80% here.  Mold is a big 
concern for us, as my wife has asthma and we both have allergies.  We 
are currently living in a 70s home that has some moisture infiltration 
issues, and just today we discovered that our expensive organic cotton 
mattress is moldy.  (Anyone know how to get mold out of a mattress?)

However, I am most concerned about the house we are building this fall.  
Positives:  it will be in a warm meadow a few miles inland with lots of 
sunshine, out of the fog.  It will be very well-insulated and will have 
hardwood floors and a house vac, and the cats will live outside 
(mostly).  None of these things are true right now; we live under the 
redwoods in the fog zone with wall-to-wall carpeting and unruly indoor cats.

Some potential negatives we have identified:

- The aforementioned humidity, though we can deal with that with a 
dehumidifier if necessary. 

- We are planning to use cellulose insulation.  Mold loves cellulose.  
Do the borate additives help prevent mold growth?  Since this is a 
health issue for us, should we be looking more seriously at icynene foam? 

- I am concerned about getting vapor barriers right.  We are building a 
double 2x4 wall on 2x10 plates, with plywood sheathing and stucco 
outside, plaster inside.  I have been expecting to use a vapor barrier 
outside the plywood.  Should I plan for a barrier under the interior 
plaster as well?  How about in the floor?

- Our building cycle is very close to the winter rains, as our escrow on 
the property in question has dragged out unceasingly.  We are worried 
about embedding moisture in the house as we build it, particularly as we 
are building with green lumber that we will be milling on-site.  Right 
now the plan is to get the framing, sheathing, and roof done before the 
winter rain starts and work on the interior carpentry all winter, and 
probably won't put in the insulation until next spring in order to get 
the framing good and dry.  How do we make sure everything dries out 
completely before we seal things up? 

I understand that these are questions for the contractors who are 
advising us and actually doing the bulk of the work, and I am asking 
them as well.  However, my experience talking with many contractors, 
engineers, architects, tradespeople, etc. in this process is that people 
often base firm opinions more on their limited experience than on 
widespread research.  Also, many people don't necessarily see mold as a 
serious problem. 

Any advice is helpful!

thanks