i'm about to embark on a project involving building a superinsulated
house with double 2x4 wall construction. The walls will be 9" thick
and will be blown with dense pack cellulose. i envision the vb going
on the warm side of the inner wall. i live in a very cold climate. i
have several questions:

which wall is load bearing? i planned on making the outer wall load
bearing, in order to shell up the structure, and adding a second wall
inside after the building is dried in. but what little info i have
been able to find talks about making the inside wall load bearing.
this is from the canadians. anybody know why you would make the inner
wall load bearing?

where the wall has roof trusses resting on it, is fire blocking
required at the top of the wall? I'm thinking not because it is full
of insulation. i'll ask my inspector, but wonder what you guys think.

anyone know of a website with some construction details? how to handle
the windows has me in a quandry. i'm thinking of oversizing the ro's
by an inch, and making a box of 1/2 inch plywood inside them (the
window would then sit inside this box). this would allow me to foam
the window to the box, and then caulk the vb to the box. trouble is,
nailing off the window into the edge of this plywood box may be
problematic. i'm also wondering if there would be value in putting a
9" rip of plywood on the top of the outer wall, expecially on the 2nd
story to prevent convection from the wall cavity into the attic.

if anyone's been there done that, i'd appreciate some tips. also,
please don't waste your time telling me i'm stupid for going double
wall--the architect and owner came up with this...i just build em.