[Sithsaber]

I've forgotten the proper use of these (ex: 's as in Saudi's versus Saudis) ; and whether the period goes in "." or out "a".

[Rainbow Crow]

I think the period in or out depends on English or British writing style. I forget witch is witch, through.

Saudis' means it belongs to the Saudi people, Saudi's means it belongs to someone named Saudi or maybe "the Saudi." So "the Saudi's camel" is singular whereas "the Saudis' camels" is plural.

[anna]

I've forgotten the proper use of these (ex: 's as in Saudi's versus Saudis) ; and whether the period goes in "." or out "a".

The period outside the quotation marks is British, inside is American.

Rainbow Crow is right about the apostrophes:

's is singular possessive, s' is plural possessive, and no apostrophe is plural non-possessive.

[Potemkin]

's is singular possessive, s' is plural possessive

An exception is made if the singular word ends is a double 's' (such as 'princess' for example), where only an apostrophe is added in order to avoid having three 's'es in a row. This means that it is correct to write "the princess' horses" if there is a single princess who owns horses, and "the princesses' horses" if there are several princesses who own horses.

[Heisenberg]

whether the period goes in "." or out "a".

RC is right; this is generally a British vs. American thing. The British style is to put the period full stop ( ) outside the quotation marks, whereas the American style puts punctuation on the inside. An exception, in the British case, is made when the punctuation is part of the original quote, for example:

1. John asked, "are you coming?"

rather than

2. John asked, "are you coming"?

I personally think the British style is better, because it prevents punctuation from changing the essence of the quote.