Detailed listing of the individual entries:

Retells the story of Annihilation from Annihilation Day minus 41, minus 40, minus 7, Annihilation Day, plus 7, plus 11, plus 12, plus 15, plus 17, plus 19, plus 20, plus 21, plus 29, plus 40, plus 41, plus 46, plus 47, plus 48, plus 52, plus 55, plus 65, plus 66, plus 68, plus 79, plus 88, plus 95, plus 99, plus 183, plus 204, plus 206, plus 212, plus 220, plus 222, plus 227, plus 268 (Armistice Day), plus 274, plus 277, plus 281, weeks later.
Based on stories by Keith Giffen, Dan Abnett, Andy Lanning, Javier Grillo-Marxuach, Simon Furman, Christos N. Gage, Stuart Moore

Detailed listing of the artists, the Chosen are marked with (*):

In November 1971 the 10th Anniversary Fantastic Four (I) #1 was celebrated by publishing many magazines with about 50% more story pages.
From FantaCo Chronicles #3: "Back in 1971, when 32 page comics were selling for 15 cents, DC comics suddenly switched over to 48 pages for a quarter, filling out the balance of their books with reprint material. It took Marvel a few months to react, but with their books cover dated November 1971, they too switched over to the new size and did DC one better by printing all new 34 page stories." (Thanks to Dan Sanders for the quote.)
Barry Pearl adds to this: "The conversion to giant-size was a costly and unprofitable thing to do. Marvel let everyone know that this was the permanent way they were going. DC signed long terms contracts to produce 25 cent comics for a year and they lost a bundle. Goodman quickly reverted back to the smaller size BUT made his comics more profitable to the retailers. This hurt DC hugely. Boy, was DC angry at Marvel."
On the other hand, the price for the extra-sized issues was raised from ¢15 to ¢25. The next issue had the normal page size again, but a prize tag of ¢20, which caused Marvel some problems because of the Wage and Price Freeze during the Nixon administration.

In November 1971 the 10th Anniversary Fantastic Four (I) #1 was celebrated by publishing many magazines with about 50% more story pages.
From FantaCo Chronicles #3: "Back in 1971, when 32 page comics were selling for 15 cents, DC comics suddenly switched over to 48 pages for a quarter, filling out the balance of their books with reprint material. It took Marvel a few months to react, but with their books cover dated November 1971, they too switched over to the new size and did DC one better by printing all new 34 page stories." (Thanks to Dan Sanders for the quote.)
Barry Pearl adds to this: "The conversion to giant-size was a costly and unprofitable thing to do. Marvel let everyone know that this was the permanent way they were going. DC signed long terms contracts to produce 25 cent comics for a year and they lost a bundle. Goodman quickly reverted back to the smaller size BUT made his comics more profitable to the retailers. This hurt DC hugely. Boy, was DC angry at Marvel."
On the other hand, the price for the extra-sized issues was raised from ¢15 to ¢25. The next issue had the normal page size again, but a prize tag of ¢20, which caused Marvel some problems because of the Wage and Price Freeze during the Nixon administration.

These characters are analysed by Cap (each character gets about half a page with a pinup and action shots):

My uneducated guess is that the pages featuring the individual Avengers during the fight are drawn by the guest art teams that are familiar with the character. Also, it fits the order in which the guest artists are credited.
Double-splash page Avengers vs. Hood's gang by Bryan Hitch and Rain Beredo
Iron Fist page by David Aja and Dave Stewart (The Immortal Iron Fist)
Luke Cage page by Michael Gaydos (Alias)
Ronin and Mockingbird page by David and Álvaro López (New Avengers: The Reunion)
Spider-Woman page by Alex Maleev (Spider-Woman (IV) (Jessica Drew))
Spider-Man page by Steve McNiven, Dexter Vines and Morry Hollowell (The Amazing Spider-Man (I) cont. at the beginning of Brand New Day)
Wolverine page by Leinil Yu, Mark Morales and Dave McCaig (The New Avengers (I))
Captain America page by Steve Epting (Captain America (V))
Ms. Marvel page by Greg Horn (many covers for Ms. Marvel (II))

Story ends with nine double-splash pages, I assume these were done by the "Flashback artitst".