No. Not only because the antenna and solar panels will likely break, but Rosetta will receive a self-kill program initiated 10hrs prior to impact, which will shut off all systems on expected impact time. This is in part due to regulations regarding the deep space radio networks.
No. As far as I'm aware, there exist no regulations regarding SETI interference (mainly because this is a private endeavour and regulations would need strong international political support).
As soon as Rosetta hits the surface, its main systems will be turned off, including the attitude and control systems, as well as the main transmitter, the latter in order to meet regulations aimed at avoiding interference on deep space network communications channels.
Sorry, I have no further info on what these regulations are.
If Rosetta crashed but remained operational enough to keep an open connection but not enough to receive commands to close it, it would use up incredibly valuable resources on a highly resource-constrained network.
I don't really understand that. DSN antennas are highly directional because they have to be. If they don't aim directly at the asteroid -- and we're talking a tiny fraction of a degree of beamwidth -- they won't hear anything, even if they want to.
There is no conceivable risk of "jamming" the DSN.
I suppose it's not about "jamming" but rather "accidental overlap" with future trajectories, i.e. another mission may pass through the axis between DSN-station and comet and the signals will mix.
Be aware that the beam is conical, so even if the pointing is exact within a few fractions of a degree, the further away you are from the DSN-station, the wider is the coverage area of the beam (and the lesser the signal strength, of course).
