Off to the side, meanwhile, Eight Rules was fit to burst with vexation; the idiot thrust out his snout and grumbled: "There's no counting the monks in this world, but not one is as spineless as this old monk of mine!

努著嘴 is a pig shoving his snout out in a sulk, which is exactly the picture wanted. 罷軟 (bà ruǎn) is "spineless, feckless, a wet blanket" — Bajie's verdict on a master who will not let anybody eat. 惱壞了: vexed to bursting. And note the grudge underneath it. The reason nobody is eating is that they are waiting for Wukong. (著 is zhe, 數 is shù, and both instances of 子 are the toneless suffix; 那 points, nà.)

"Here's food ready and waiting, and he won't take even a third-share of it, but must hold out for that monkey to come and make it a quarter-share before he'll eat!"

Here is the whole of Bajie in one piece of arithmetic. Food divided three ways is a third each. Wait for the monkey and it becomes a quarter each. That is his objection to waiting, and he has worked it out to the fraction. 倒 (dào) is the adverb of grievance — won't eat it, if you please. The 兒 of 三分兒 is the small toneless tag; 那猴子 points, so nà, with 子 as the suffix zi.

And without another word he shoved the jar over with a thrust of his snout and was about to fall to.

拱 is what a pig does with its nose, and he does it to the jar. Watch the character that has just changed jobs: this 倒 is dǎo, "to topple over", where the one a line above was dào, the adverb of complaint. 不容分說 is "without waiting to be argued with". He is about to eat — and if he had, he would have found what is actually in that jar and blown the whole scheme open. Greed very nearly saves everybody.