About the carb heat - I was also taught to turn it off before touchdown - perhaps at 200 ft. Last thing you need on the roll out before a go around is an extra lever to remember to move.
The problem is, "about 200ft" can be 30 or 40 seconds before power is re-applied with the engine at idle (or nearly), plenty of time for ice to build up I would have thought. I can see the point in teaching students to do things really early, but I tend to delay a bit and go to cold just a few seconds before crossing the fence (or forget completley of course
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I suppose the thing with the flaps depends on the aircraft really - with plenty of power, leave the flaps down. If marginal, get them at least partially up ASAP. One-up in a pa28-161, you can still get 600fpm climb with full flaps (I know, 'cos I sometimes forget to retract at all
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