If you are writing words, yes. But it looks better to say 5:30 rather than five-thirty.
You do not need to hyphenate.
No. It is three thirty, but in five minutes time it will be three thirty-five.
Sure, honey, you hyphenate "30 minutes" when it's being used as an adjective before a noun, like "a 30-minute workout." But if it's just hanging out by itself, no need for that hyphen. Keep it sassy, darling!
Six times five is thirty
You don't.
No, "thirty first" should not have a hyphen. It is written as two separate words when used in a sentence, for example, "The event is on the thirty first of July." However, if it appears as an adjective before a noun, you can hyphenate it as "thirty-first," such as in "the thirty-first day."
Thirty five Thirty-five
The time 'two-thirty and thirty-five seconds' would be written: 2:30:35.
Thirty five.
Thirty-five thousandths
thirty-five-hundredths = 0.35
Thirty-five hundredths