Laser snipers

SG says snipers sometimes carry laser weapons.	However, I recall a
discussion in which it was said the x-ray lasers so beloved of my
Traveller
characters would hardly be silent/invisible--more like a lightning bolt.
Don't know whether that was accurate, though.

So, questions for you educated blokes:
a. would/could a military laser weapon be invisible/inaudible?	Or would
it
be useless to snipers due to signature?  (assumes a standard Earth
atmosphere with no unusual components)
b. in a zero gee environment, would lasers have *no* recoil?  This
doesn't
seem logical because we've talked about a lasers as a ship drive, so
there
has to be some recoil....but how much?	Either as compared to a rifle,
or in