The analyses of a text #2

The narrator recalls his adolescence.
He was an apprentice for Mr. Spenlow.
He and Mr. Spenlow's only daughter Dora fell in love with each other.
Now He is married to Dora in their own house.

.................................
Everybody we had anything to do with seemed to cheat us. Our appearance in a shop was a signal for the damaged goods to be brought out immediately. If we bought a lobster, it was full of water. All our meat turned out to be tough, and there was hardly any crust to our loaves. In search of the principle on which joints ought to be roasted, to be roasted enough, and not too much, I myself referred to the Cookery Book, and found it there established as the allowance of a quarter of an hour to every pound, and say a quarter over. But the principle always failed us by some curious fatality, and we never could hit any medium between redness and cinders.
I had reason to believe that in accomplishing these failures we incurred a far greater expense than if we had achieved a series of triumphs. It appeared to me, on looking over the tradesmen's books, as if we might have kept the basement storey paved with butter, such was the extensive scale of our consumption of that article. I don't know whether the Excise returns of the period may have exhibited any increase in the demand for pepper; but if our performances did not affect the market, I should say several families must have left off using it. And the most wonderful fact of all was, that we never had anything in the house.
[David Copperfield by Charles Dickens]
1. I think "it" refers to "meat" and the subject of "say" is "the Cookery Book."
So I was wondering why the subject of "say" is omitted.
2. I'd like to know what "we might have kept the basement storey paved with butter" means.
3. I'd like to know why "and" is omitted before "such."

Thank you in advance for your help.