i gave up on buffy about the same time Angel started, i couldn't be doing with Reilly and just stopped watching, and Adam - Resident Evil people, he was the freaking nemesis.

but i know my way around angel like the back of my hand.
it's at the end of series 1 he learns about the shanshu prophecy (the ep is From Shanshu to LA) and they spend the next four series deciding what it means and they never agree. Christian Kane's character (who has a girly name I can't remember - the lawyer) starts it with bringing back Darla.
the prophecy suggests that if he does enough good deeds the vampire with the soul will become human again (but this also applies to later series spike) but it also might mean that he will die, that he will be sent to hell or all of the above. Wesley never does decide on the translation.
but, this is where Angel (imho is more adult than buffy) there is a few instances where they use prophecy against them, the whole thing with Angel's child where wesley reads that the vampire will eat his son becomes paranoid and to protect the child sends him to holtz. but it turns out that the guy who wrote it (again the name escapes me but he has real monster face and lives in a hole - brought holtz back from the dead) actually wrote it because the child will be the one to kill him and wanted to prevent that.
so, to summarise you can't trust a prophecy in angel because Wesley might not be able to translate it or it might have been put in place by an interdimensional force as a wind up.
and they never do go back to the PTBs

hope this helps