I actually posted on this very thing quite a bit elsewhere, but Angel and Faith and Buffy are both blanketed under the title of "Season 9". They both pick up following the events of "The Last Gleaming".
Angel AtF and the books that follow all take place before Buffy Season 8. Most of the stuff IDW produced is really good (Vol 5: "Aftermath" being the exception but it set up what's to follow).
Here's a list of recommended comics/reading order for you 🙂
Joss Whedon's Fray
Buffy the Vampire Slayer: Tales (new deluxe hardcover combining the Tales of the Slayers and Tales of the Vampires trades with the Tales of the Vampires stories from Season 8 - GORGEOUS!) Read Tales of the Slayers and the original Tales of the Vampires at this point.
Angel: After the Fall, Vol 1
Angel: After the Fall, Vol 2 - First Night
Spike: After the Fall
Angel: After the Fall, Vol 3
Angel: After the Fall, Vol 4
Angel: After the Fall, Vol 5 - Aftermath
Angel: Vol 6 - Last Angel in Hell
Angel: Only Human
Angel: Special - Lorne (back issue)
Angel: Vol 1 - Immortality for Dummies
Spike: The Devil You Know
Angel: Vol 2 - The Crown Prince Syndrome
Angel: Illyria - Haunted
Spike: Vol 1 - Alone Together Now
Angel: Vol 3 - The Wolf, the Ram, and the Hart
Spike: Vol 2 - untitled (August 30 release)
Angel: Yearbook (again, a back issue, but the very last deluxe issue of IDW's stellar run; great stories in this one including a touching Wesley-Fred piece)
Buffy the Vampire Slayer: Season 8, Vol 1 - The Long Road Home
Buffy the Vampire Slayer: Season 8, Vol 2 - No Future for You
Buffy the Vampire Slayer: Season 8, Vol 3 - Wolves at the Gate
Buffy the Vampire Slayer: Season 8, Vol 4 - Time of Your Life
Buffy the Vampire Slayer: Season 8, Vol 5 - Predators and Prey
Tales of the Vampires: Season 8 from BtVS: Tales
Buffy the Vampire Slayer: Season 8, Vol 6 - Retreat
Buffy the Vampire Slayer: Season 8, Vol 7 - Twilight (read "Willow: Goddesses and Monsters" at the end of the book before reading "Turbulence" and "Twilight"; even though it takes place before S8, it's publication order places it at this point as a flashback)
Buffy the Vampire Slayer: Season 8, Vol 8 - The Last Gleaming (read "Riley: Commitment through Distance, Virtue through Sin" at the end of the book before reading "The Last Gleaming"; even though it takes place before S8, it's publication order places it at this point as a flashback)
