A comma followed a incomplete sentence with a conjunction

I'm Korean, and I have never been to nations spoken English. Please, Would you have this in mind?

I have read a book the name of which is 'Eats, Shoots & Leaves' and assured myself that 'the comma filling gaps' ,which I had seen in the internet at several times, is grammatical
; As I had been curios of whether it is grammatical when I knew that, I was very much delighted.

Anyway, I have two questions.

1) In the following two sentence, commas were followed by incomplete clauses with 'and'. I'd like to know whether these are grammatical.
a) There is no accounting for taste; to some, reading is pleasure, and to other, suffering.
b) Trucking company Move-All noted that the slow economy results in less freight being moved, and therefore reduced revenues for the company.

2) In the following two sentences, the second clauses have a subject without a verb. I'd like to know which is grammatical - a) or b)
a). Kiwis weight about four pounds and theirs egg about one pound.
b). Kiwis weight about four pounds, and theirs egg about one pound.

Furthermore, I'd like to know whether the usage of comma as the above sentences is quite the thing in the spoken English.

In advance, Thank you for your help.