No
A period should come before the footnote at the end of a sentence, while a comma should not.
Yes
If a comma is needed, it normally comes after parenthesis.
The comma would come after it.
No, a comma before "as appropriate" is not necessary. It depends on the context of the sentence and whether it flows better with or without the comma.
no . Additional: 'Which' sometimes has a comma before it, but it depends on the sentence. I find it hard to imagine a situation when 'which' would have a comma after it.
Return to sender does not require quotation marks or a comma.
It is usually appropriate to place a comma before "but." One should not use a comma after "but."
No, a comma does not always come before "for instance." It depends on the structure of the sentence. A comma is typically used before "for instance" when it introduces a non-essential or parenthetical element in the sentence.
A comma should typically come before the word "but" when it is used to connect two independent clauses. If "but" is used to join two elements within a single clause, then a comma is usually not necessary.
The comma typically comes before the conjunction "but" when it is used to connect two independent clauses. If "but" is used to connect two words or phrases within a single sentence, a comma is not necessary.