Re: acceptable expressions or not?
It's best to ask unrelated questions in separate threads.
I don't know why it took Mary an hour to do the homework. It took me five minutes to do it.
I watched TV all night long. Well, not ALL night. I took five minutes to do homework.
Do you see the difference?
If you simply want to say how long you spent on an activity and that you completed it, the more natural way to say it is "It took me..."
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.