EricFusco

Two reasons for why the Russian "weather satellite" was able to fend off the UFO attack: the rogue machines we saw in the movie were all in AMERICA, so they spoke ENGLISH. And if science fiction TV shows and movies have taught us anything it's that all aliens speak English (and if they are really advanced, with British accents). The "weather satellite" spoke Russian, so it was unable to understand the commands of the aliens and therefore could fend off their attack - unlike the American "weather satellites"!

Keep in mind I have not see Xanadu since it was first on HBO in the 80s, That said, I interpreted the ending as that Kira had decided to become mortal and stay with Sonny, but by giving up her immortality she also gave up her identity/memories. That's why she didn't recognize him in the end.