[DS2]Moon - Help Requested

I am going to run a DS2 game at the GZG-ECC. It is based on the Moon.
I need some help:

1. First, I need some help with DFFG's in a vacuum. At first, I was of
the opinion that they would have a longer range, since it would not
diffuse into the (nonexistent) atmosphere. In this, I pictured that it
was held in magnetic containment for the full distance to the target.
After a closer reading, the plasma is not contained once it leaves the
barrel of the gun. Having never taken a physics class, my question is:
Would the plasma remain as a cohesive ball of gas, maintain the same
dispersal pattern or be even more quickly dispersed?

2. Second, the Moon is about 1/6th the mass of the Earth. However, it is
less dense (and contains fewer heavy metals). But I have been unable to
find what the circumference of the moon. I am trying to figure out the
distance to the horizon on the Moon. If anyone can provide information
or insight on this matter, it will be appreciated.

Brian Bell
bkb@beol.net