Rule for adding "and" or hyphens between numbers that are spelled out fully in text

Three hundred and forty-two

Leaving out 'and' is more common in US English. Either is acceptable, but including 'and' is more correct.

Hyphenate all compound numbers between twenty-one and ninety-nine.

I was always taught, in American English, to use "and" only with compound numbers such as "three and three-quarters." Wikipedia also mentions this:

Note that in American English, many students are taught not to use the word and anywhere in the whole part of a number, so it is not used before the tens and ones. It is instead used as a verbal delimiter when dealing with compound numbers. Thus, instead of "three hundred and seventy-three", one would say "three hundred seventy-three". For details, see American and British English differences.

And as ElendilTheTall said, hyphenate numbers between twenty-one and ninety-nine as well as fractions.