Hi Spatsycat,
That's pretty cool that you saw a Crossbill at your nyjer feeder, I didn't know that they could manage such small seed with that crazy bill of theirs. Don't know if you've seen Pine Siskins before or not but check your first 2 photos again if you haven't, the bird with it's back to the camera looks like it might be a Siskin. They're Goldfinch size but have dark streaking over their back and breast, also, they have a very narrow pointy beak. Right now, the city is filled with Pine Siskins and White-winged Crossbills.
Happy Birding!
Walter