Thrawn is a space-only hero similar to Piett. Garm does have a "fleet commander" style bonus when in space.
It looks like most of those shots were taken in Bespin orbit. We've lowered the altitude of the space battle over Bespin just a bit
The Arc hammer is somewhere between the length of a Victory and Imperial Star Destroyer, but obviously much thinner. The load out is pretty basic, similar to a Victory's hard points but with an added concussion missile point.
The Lancet is mostly used as an aerial artillery unit, but it can be put to other uses...