I wonder if it'll be possible for such a micro-sat to enter an orbit around
the orbiter? Will the air drag (and solar wind drag) be larger than the
attraction of the microsat to the shuttle? Assuming 100t shuttle and microsat
at 100m from it, the gravitationsl acceleration is about 6.6E-10 m/Sec^2
(unless I miscalculated something).

So v^2/r = 6.6e-10, r=100, and v = .26 mm/s, orbital period about a month.
Stick with the cold gas thrusters.