While I would agree in general with your statements re use of commas and periods, note that this is American conventional usage in which it is also quite correct to omit the final comma (just before the "and") in a series -- that comma is considered optional and only used when omission could lead to a misreading (as in your examples). American common usage further dictates that while commas and periods generally are placed inside quotation marks, one exception is if the quotation marks enclose a single letter or a number.
British usage differs significantly, however, relying more upon logic in the placement of commas and periods with regard to quotation marks; i.e., if the comma or period applies to the material within the quotation marks then the punctuation is placed within them, but if the comma or period applies to the entire sentence then it is placed outside the quotation marks.
Newly