Not any more
It is common to do so, but not good form. For example, the number 1,097 should be written "one thousand ninety seven" not "one thousand and ninety seven". Similarly, the number 1,197 should be written "one thousand, one hundred ninety seven" not "one thousand, one hundred and ninety seven.
There are a number of situations which would be inappropriate to use a comma in. The common ones include when breaking a sentence and when stating number of items among others.
What are all the names of a comma in a number
A number cannot be turned into a comma which is a punctuation symbol.
The comma is used to separate similar words. 2011 is a number and January is 'text'. Therefore no comma is needed. But you would want to use a comma to separate two numbers. Hence January 11, 2011.
No. After the word and comma can not be used, as it is grammatically inappropriate to use comma after conjunctions such as and, which are called coordinate conjunctions.
No, a comma is not necessary.
after the third number
no
no
You can use a comma after an opener , so if it is 'Finally' the opener you are talking about, then yes.
In a company name such as "ABC Corp," do not use a comma. However, use a comma in the formulation, "ABC, Inc."
You can use ", and" or just "and" but not just a comma.