The question about icing at 2000ft was probably a question about the rain ice triangle. The correct answer is either to climb into the warm air above, or to descend; all things considered I gather that the option to go for is to climb into the warmer air. The one thing that you do not want to be doing is turning around. If you have come so far through icing conditions then the turn and the associated retreat will load you up with at least the same amount of ice again as you have already collected – that might really spoil your afternoon.
The worst icing is from 0 - -10 deg
When diving to in excess of 10m you should not fly for at least 24 hours. This is not due to Hypoxia, but Nitrogen Narcosis (I think someone has already mentioned this). Nitrogen is absorbed into your blood stream under pressure when diving and if you surface too quickly the nitrogen gas expands faster than it can be released from the blood.
The question about the highest lat – the third option was 23, rather than 33 deg and I think that this is correct. The tropics of cancer and Capricorn are at 23.5 deg N and 23.5 deg S respectively and these are the points furthest N and S that the sun will be directly overhead at some time during the year.
Hope you did OK