Time!
This type of question for JAA ATPL is a waste of time, so trying to do it quicker is a waste of time too. If JAA ever ask this type of question, I'll eat my hat!.
All you need to know about Foehn for the JAA is this.
Warmer on ther lee side, higher cloud on the lee side, possible turbulence on lee side (from possible mountain waves) and you need to know the other names for the Foehn, e.g Santa Ana and Chinook.
Now for some lovely spuriouis info. The Foehn translated actually means "Hair dryer" in some European languages, so remember it as a warm dry descending wind, or a warm katabatic.
One more thing, if your School is using 1.5°C per 1000ft for the SALR in their ATPL notes they need shooting and they need to be reminded of the JAA METEOROLOGY OBJECTIVES.
Good luck anyway, met can be a nightmare unless your taught right, wait till you get to winds!!!
Have fun