Same as title
Like which one is positive and negative? It shouldn't matter for power/reset. I think only the leds have to have +- oriented correctly.
The header should be marked and the manual should have a nice diagram view.
Read your mobo manual. There should be a section that's labeled front panel headers or something similar
Instructions in the mobo manual. If you have misplaced it, you can download the manual from the ASRock website.