Re: Standard land rules
You're allowed to use whatever basics you like, regardless of which set they're from as the standard five lands are reprinted in every set. Many people play with the full-art lands from Zendikar or the Un-sets simply because they're often more fun to look at.
Re: Standard land rules
You can use any version of any card currently in print, provided that the name is the same. So for example you can use Alpha Giant Growths if you want instead of M14 Giant Growths, but you can't use a Llanowar Elves in place of Elvish Mystic. This rule also applies to Basic lands. You can run all the Plains you want from any set, but throw a Snow-Covered Plains in there, and you'll have a problem.