Quite a few corrections, bear with me here...

Syd Barrett does not sing on "Corporal Clegg" or "It Would Be So Nice," but producer Norman Smith does (he's also heard on "Remember A Day"). This is according to Nick Mason's book Inside Out. Smith probably also appears on "A Saucerful of Secrets" and "See Saw," but this is conjecture.

Someone speaks a few words of "Candy and a Currant Bun" and "Apples and Oranges," perhaps it's Syd but I think it's more likely to be Nick. Plus you can very clearly hear Rick's harmony vocals on "Candy" and "Bike." It's also said that Roger and Nick sing backup on "Arnold Layne" and "See Emily Play" but I can't verify this, nor hear any trace of it.

Roger whisper-sings backup vocals on "Matilda Mother" and "Let There Be More Light" (which does not feature Syd). Again, refer to Inside Out. He's on "Julia Dream" too, whispering "sssssave me!" during the chorus. You can also hear Roger's distinctive vocal sounds on "Flaming," "Paintbox," "The Gnome" and "Point Me At the Sky." But I don't think he's on "Crying Song."

Dave scats along with his guitar on "Careful With That Axe, Eugene." I don't think Rick is on the studio version of "Embryo" even though he sang it live. The person speaking on Atom Heart Mother ("silence in the studio!") is orchestrator Ron Geesin. The choral vocals are by members of the John Aldiss Choir, but on live versions they're sung by Rick and Dave. Nick doesn't speak on Alan's Psychedelic Breakfast, the eponymous roadie Alan Stiles does. And I think you forgot about Dave's vocals on Summer 68 ("how do you feeeeel").

Clare Torry doesn't sing on "Eclipse," it's Doris Troy. The soul singers on "Time," "Us and Them," and "Brain Damage/Eclipse" are her, Leslie Duncan, Liza Strike, and Barry St. John. Two members of the Blackberries, who sang these parts live, also appear on "Not Now John" and "Shine On You Crazy Diamond": Vanetta Fields and Carlena Williams.

It's Roger, not Rick, who harmonizes with Dave on "Welcome to the Machine" but I think it's just Dave on "Wish You Were Here." Rick sang on the live versions of "Dogs" so he might be in the studio mix, too. There's a chorus of Floyd roadies who speak the middle passage in "Sheep"... they also chant on "Waiting For the Worms", "Run Like Hell" and "The Trial".

Dave adds harmonies to "Another Brick in the Wall (Parts One and Three)", "The Happiest Days of Our Lives," "Don't Leave Me Now" and "Run Like Hell." The kids on "Another Brick in the Wall (Part Two)" and "Outside the Wall" are the children of Islington Green Primary School, Fourth Form. The "Beach Boys" are actually Bruce Johnston, Joe Chemay, John Joyce,
Stan Farber and Jim Haas. Toni Tennille does the spoken word on "One of My Turns".

Darlene Koldenhaven, Carmen Twillie, Phyllis St. James, Donnie Gerard sing on "Learning To Fly," "The Dogs of War," "One Slip," "On the Turning Away," "Yet Another Movie," "Terminal Frost," and "Sorrow." Dave sings lead on "The Dogs of War," and Rick only appears on "Sorrow."

Rick doesn't sing on "What Do You Want From Me," "Take It Back" or "High Hopes," but Dave takes a verse of "Wearing the Inside Out." The backup singers on "What Do You Want From Me," "Poles Apart," "A Great Day For Freedom," "Wearing the Inside Out," "Take It Back" and "Keep Talking" are Sam Brown, Durga McBroom, Carol Kenyon, Jackie Sheridan and Rebecca Leigh-White. They also sing on "Marooned," which you forgot to list. Speaking of omissions...

Vegetable Man - Syd, Nick, Roger
Scream Thy Last Scream - Syd, Rick, Nick
A Spanish Piece - Dave
Seabirds - Roger, Dave
Heart Beat, Pig Meat - Roger
Crumbling Land - Dave
Come In Number 51, Your Time Is Up - Roger, Dave
Country Song - Dave
Speak To Me - Clare Torry
When the Tigers Broke Free - Roger
Signs of Life - Nick

...there are also some high-pitched sped-up voices on the studio versions of "Scream Thy Last" and "Embryo" that I cannot immediately identify. Nick maybe?

__________________
what do you teach your children about me?
what do you teach your little children about me?
pimp, thug, bling drug lord of the undergrounded kings
how can you be so sure i won't call down the rain?
what do you teach your little children about me?
you point your gun, wait, hide and run. i see it plain