English question, please help?

Actually, for the second part of your query, both are correct but mean different things,

"I ran for two hours." refers to a specific occasion in the past where you were running continuously for two hours. For example, "John woke up in an energetic mood yesterday so he drove out to the National Park and he ran for two hours."

"I have run for two hours." means that, on at least one occasion in your lifetime you started running and did not stop until two hours later. For example, "I like to run everyday; I usually run for one hour but I have run for two hours."

Since I'm no grammar Nazi all I can say is that both are fine, BUT I would only say the first of each of your example sentences because they sound 'right' to me.

I have run for two hours is correct though a bit weird because in general people would say "I have been running for 2 hours", give a little bit -ing to it to make it seem more on-going

The first one How's their life in Australia is correct The second one is incorrect

The first one I ran for 2 hours is correct, the second one isn't

Hope this helps