That achievement by all four openers in the first innings in Rawalpindi is indeed unique. There's one other Test in which all four openers made hundreds - in Port-of-Spain in 1947-48 - but England's were spread over the first innings (140 by the debutant Billy Griffith) and the second (133 by Jack Robertson). West Indies' hundreds were scored by George Carew, in his second Test 13 years after bagging a duck in his first, and Andy Ganteaume, who famously never played another Test match.
For this sort of question I needed to consult the Melbourne statistical wizard Charles Davis, who has made a study of hundreds of old scorebooks. He says, of England's lunch score on the first day in Rawalpindi, "174 is second, after 179 for 1 by South Africa against Australia in Johannesburg in 1902-03. That involved about 41 overs, whereas England faced only 27. Earlier that year in the Ashes, Australia made 173 for 1 off 33 overs at Old Trafford, an innings which included Victor Trumper famously making a century before lunch."
The seven centuries scored in Rawalpindi was one short of the Test record of eight, set by West Indies and South Africa in Antigua in 2005, and equalled by Sri Lanka and Bangladesh in Galle in 2012-13.
The 34-year-old legspinner Zahid Mahmood had an expensive debut in Rawalpindi.
You're right that the Australian fast bowler Mitchell Starc bowled the West Indian debutant Tagenarine Chanderpaul in the Test that finished at the weekend in Perth - and back in 2012, in one of his early Tests, he trapped Shivnarine Chanderpaul lbw in Dominica.
Steven Lynch is the editor of the updated edition of Wisden on the Ashes