My regex skills are not so polished either, but let me know how I do:

1: m/^([.]*)[^,]"\s*$/
2: m/^([.]*),\s$/
3: m/^(.*)$/
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Note: for #1, I am not sure if by "without a preceding" you be no commas or just not one before "

I suggest not creating one regex to "rule them all"; instead check for each line in the order of precedence that you want; for example, #1 is probably your 'catch-all'.

Your question is actually very general, so if you are looking for more specific help in doing something, you need to get more detailed.