Will see if I can answer the questions (may 
duplicate a few things others have sade).

1. The sketch paper is thinner than your other 
sketches. Sketch paper can vary in a series, 
especially in OVA depending on what is going on. 
For still shots and low movement shots, they will 
use thicker paper. In high movement shots, they 
will also use thinner paper in order to make sure 
that the movement is transfered logically from one 
cel to the next. This is especially the case for 
key cels which serve as the guide and which will 
be used by the in betweeners as a reference for 
what they are drawing.

3. Why is the sketch not damaged, but paper is 
stuck to the cell. It was probably stuck to 
something else. The last batch of Gunnm cels that 
were released in japan were all backed with 
something other than the sketch paper. One of my 
new ones has stuck paper, but the sketch is not 
damaged. Having paper stuck to a cel is much more 
effert than any fan cel producer would ever try to 
do and would not add to the value anywasy (so why 
do it).

4. Why is a middle cel a key cel. Key cels often 
appear in the middle of sequence. From the few 
large sequences I own, I usually find up with a 
key cel every 4-8 cels. In a segment with 60 cels, 
I would expect at least 10 key cels (first and 
last and 8 in between). Since this segment had 
complicated movement and body positioning of gally 
in it, it probably was more key animated due to 
the difficulty of the drawing.

5. Why is the cel brighter than other cels in the 
sequence. There were bright and dark segments in 
that sequence as she transitioned in and out of 
light. Have you located your other cels and found 
out if those are from segments were she is more in 
the dark.

6. Why does the sketch coloring look weird. The 
colors and painting by this time is probably very 
well known (they just painted a lot cels before 
they got to this one). The only reason there 
probably is any sketch color is that this is a key 
cel. The only indication of color at this point is 
probably of segments which are transition in color 
from shadow to light color selection. Not 
completely sure what you are refering to on being 
different on the sketch.

2. I can't answer. That is weird. Who knows. For a 
fan cel artist to do this, it would take a lot of 
time and there is no reason a fan cel artist would 
go through the trouble of punching holes in this 
manner, rather than in the standard manner.

My two cels.
Marcus