I would write the first word after the period in capital case, as you did in the second sentence you wrote.
The general rule of writing a word in capital case after a period is still valid even if you write a single word and then a period.
In those cases, the periods are used to give an emphasis to the single words. The pause when "reading" a period is longer than the pause used for a comma; for this reason I would not say the periods are like commas, in the examples you wrote.
Like all comprehensive answers about English (or those attempting to be so), this answer begins with, “it depends”.
A quotation that is not a complete statement should never have a period within its quotation marks:
The senator, when asked why he refused to support the measure, said that the language of the bill was “confusing and verbose”.
“Confusing and verbose” is not a complete statement; the quotation is simply attributing these exact words to the senator, while summarizing his complete statement largely through omission.
By contrast, a more complete statement attributed to the senator CAN have the period inside the quotes:
The senator, when asked why he refused to support the measure, said: “The American people deserve to understand the laws their representatives in Congress are writing, and this confusing and verbose bill hinders that effort.”
Now, it is still acceptable to place the period outside the quotation marks in this case. However, if the quotation spans the entire sentence from capital letter to fullstop, and/or continues for multiple sentences and comprises a full paragraph, the quotation should enclose the final period.
Best Answer
The general consensus seems to be that there is never an acceptable use of two sequential periods. A period at the end of an abbreviation is adequate punctuation when a period would end the sentence naturally. If any punctuation mark other than a period is needed, that may be added. Similarly, within a sentence, as when a comma would be appropriate, that may be added.