scan office documents, used COLOR or BW ?

[gonnal]

I have problem.

I need scan office documents (something some Invoice, Letter that documents)
but that documets letter is very light color AND
that A4 paper is wrinkled.
finial, I will goto Acrobat to convert ".TIFF" > ".PDF"

Now,

(Q1) if scan used "Color" and
....Set to BitMap Output : 50% Threshold

OR simple... used "BW" to scan?

which method is best? what difference?

(Q2) do you know that "BW", "Color" , and that "Gray"
what is "Gray" , is COLOR or "BW" mode ?

please!


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I'm used Photoshop 7 and HP scanner (max: USB1.1 standard. NOT version.2)