M.85,
With regard to the first question, and whiping away the cob webs of my ATPL memory banks, Buy Ballots law also applies to warm and cold air. The question asks what happens to the OAT. In the NH with your back to wind the cold air is on your left, therefore when flying north, wind from the left would indicate a westerly wind. So with that in mind, the cooler air is to the north, and the warmer air is to the south, therefore the given answer is correct, the air temperature will increase north to south.
This type of question is very typical in the MET exam, and the answers will also be worded in such a way as to confuse you, so read them very carefully.
Good Luck