Towards the end of season 3 she left off with groo for a couple of episodes i thought that it was vary stupid of a thing to write into the show because the time she was gone could hvae been used to develop her half demon powers and explained what they meant. I heard that something happened to Charisma is that true?
I'm 90% sure she had a death in her family.
They weren't too happy with her "Playboy" layout, and then real life pregnancy and subsequent weight gain didn't seem to fill their hearts with joy, either. I think the official story was that Charisma and the producers "through mutual agreement" to go their separate ways. The next season's guest appearance might have been just to see if the fans wanted her back the way "Something Blue" was a test to see if the fans would accept a Buffy/Spike romance. At least, that's the story as I heard it.
Well I'm pretty sure Joss' people said that Charisma was looking for a traditional maternity leave (/family time) like normal jobs give, but it wasn't possible for them to give it to her on
Angel for obvious reasons. I think she was going for like a 14-episode commitment (out of 22) with her normal salary, which Joss & co. weren't willing to do.
Joss' official answer at the time was something along the lines of "I think the Cordelia character has reached her full potential."
As far as "You're Welcome," being written as a test to bring her back, I'm pretty sure it wasn't. Joss originally wanted Sarah Gellar to be the one who puts Angel back on his path, but she wasn't available. Contrary to popular belief, Sarah was never meant to guest in TGIQ, they never intended for Spike & Angel to see Buffy then. There were actually a lot of guest spots in S5 that didn't work out:
"The Girl In Question" - Joss wanted Michelle Tractenberg to be the one in the apartment, but they couldn't get her, so Andrew was used instead. Joss was pretty unhappy because apparently some of the stuff he wrote for Dawn was just given over to Andrew.
"A Hole In the World" - Giles was meant to meet Angel & Spike in the deeper well, but they couldn't afford Tony Head so they created Drogan.
"You're Welcome" - like I said was written for Buffy, but they couldn't get Sarah, so it was switched to Cordy.