Campaign rules?

Hello Guys,
  As a first rule for construction times, what do you all think about
using the square root of the mass as time in months for construction
time?
Thus a 100 mass unit would take 10 months to make, while a 4 mass unit
would take 2 months to make.  Time taken is considered to be wartime
construction times where the shipyard is taking 7 days a week to make.

  Also, I would like to see if anyone has ideas about making a new
"system" called cargohold.  Cargoholds are immune to needle beams, and
each take up 1 mass unit.  If one assumes a set volume (to be specified
by
the game users, not the game rules <grin>), then cargo ships can have an
allocation to non-weapon systems that makes sense, instead of stating
that
the damage done to the ship outright determines how much damage is done
to
the cargo itself.  Thus, a mass 40 cargo ship, which can only have 4
mass
units of weaponry, can now have an additional 16 cargo units, with the
remaining "50%" of the ship treated as other warships are treated - as
having drives, lifesupport, staterooms, etc...
  If we go with my idea that each mass unit holds 250 cubic yards or
cubic
meters (for those of you who use more sensible metric conventions),
which
I arrived at by assuming the values given in FT II and by approximating
the volume of an M1 Abrams tank, then we can now begin to add a little
more "flesh" to the system...

  Comments?  Oh, one more thing.  In private email, there has arrived a
situation where one of us thinks you need one Fire Control per needle
beam
absolute, and another thinks you need one Fire Control to control a
bunch
of Needle Beams - assuming they are firing at the same "targeted
system".
Could someone point out the correct path to follow in this instance?

Hal