I think it is a great question; I suspect we are to retrieve it, but it is also nice to know our options when we are in a bit of a pickle.
Edit: I think there is an unspoken rule that (human) artifacts are generally sought to be retrieved for our own use1, but the calculation can be different if there is a significant chance of failure. For Xenos artifacts I'd say it completely depends.
Edit 2: I would not be surprised if our Techpriest would have some sort of fit over this outcome thought. I forgot we are talking about a Xenos artifact here.
Regarding your other questions:
- The Core Rule Book (CRB) has a Vox-Caster on pg.176 which can be used to communicate with a ship in orbit.
- Rites of Battle has various naval assets which can be (potentially) requisitioned: ex. a Lance/Torpedo Strike, High Altitude Bombing run, or Close Air Support. These do all require more than the starting Renown though, so I don't think they will be available unless our DM is extremely nice to us.
- Depends on the asset ;-), but the Lance strike is accurate to about 1km or when it misses, it is off by 1km/DoS, whereas a strafing run is basically an ally shooting a las- and/or autocannon at the target and hopefully hitting. So unless we are in melee, the chance of us getting hit are rather slim (Unless our DM is rather devious ;-) ).
1) from my understanding, and I could be incorrect here, almost everything from the Dark Age of Technology seen as Sacred, with the exception of AI, and possibly cloning.