Okay, for my current fic, "Future Sins Past", by the day after "Whats My Line?", did Angel have an invitation to Willow's house? I know he did at some point but I'm not sure when....

Yes, he got it in Lie to Me which was directly after the Halloween episode.

I know...not my thread, but I have a cannon question, and it seemed silly to start a new thread so...

Did the Slayer from the Boxer Rebellion, (Spike's first kill, Slayer-wise) have a name, and was it revealed anywhere in cannon? (I'm including the comics as well.)

Her name was Xin Rong, which definitely came from the comics... "Spike & Dru: All's Fair," I think. On the show, she was only referred to (and credited) as "Chinese Slayer."

You can find more information on the Chinese Slayer (Xin Rong) on Wikipedia. Here's the link.

http://en.wikipedia.org/wiki/Chinese_slayer_(Buffyverse)#Xin_Rong