Need Clarification of cost of additional Components rules

[Japper]

I am a little unclear about the use of custom parts and would appreciate it
if anyone can help me to understand the rules on the following:

I understand that the total limit of additional parts used must be less than
$3500 and if I understand it correctly, any one part used must be worth
$400 or less. Is this a correct understanding of the 2007 rules so far?

In the scenario where I were to accept a donation of an assembly that is
offered by a company and it is typically sells for $600 and is available
to anyone who wanted to buy it at that price, is it true that this part
would be not allowed because it costs mors than $400 to purchase it?

Is this value based upon the selling price of the assembly or the
cost of materials that go into the assembly?

If we were to customize the assembly or only use a portion of this
assembly, are we limited to using any one piece worth less than $400?
How would we determine this value?

If we were to take the above assembly and only use 1/4 of it, so that we
are effectively only using $150 of the value of the donated item, can we
report this as a $150 part?

Can we value the above portion of the assembly as the value of the individual components
of this assembly if we buy it that way?

One last question... What do we need to log and show to the judges regarding additional parts
used, do we need manufacturer name & contact info, part number, cost
basis, and / or what else?

Thanks!