Not sure if anyone would ever consider doing this due to the collateral damage, but I think a retrograde GEO orbit would work fine for destroying a lot of GEO Sats. You would need to spread out your impactor by detonating it but the fragments would have 6 km/s relative to the GEO Sats.
Not really, and I couldn’t find something like that from a quick googling. Maybe it wouldn’t work as good as I would think. I’m not sure if it’s really a realistic threat anyways, because polluting GEO is basically half way to a nuclear war. Kesslerizing LEO is probably bad but not forever and more easily avoided by picking another orbit. Making GEO impossible would really annoy every country out there.
