Learn English – What does “call past” mean

'Faust' is the main character in German legend. From Wikipedia:

Faust or Faustus (Latin for "auspicious" or "lucky") is the protagonist of a classic German legend. Though a highly successful scholar, he is unsatisfied, and makes a deal with the devil, exchanging his soul for unlimited knowledge and worldly pleasures.

Making a 'Faustian bargain' can be interpreted as making a deal with the devil - it may seem like a good deal, but there is always a catch, and that catch is usually very, very bad.

Here is a wikipedia article discussing 'Deals with the Devil', which they also term as a 'Faustian bargain':

http://en.wikipedia.org/wiki/Deal_with_the_devil

The trees are the right height is not an established phrase, but it describes Romney's opinion that Michigan is the ideal place. Take for example the last example you cited (emphasis added):

What a thrill it is to come back to Michigan, particularly in the winter, where the skies are cloudy all day, trees are just at the right height, almost all the cars you see are American-made - the way they ought to be

That is, the trees are the right height because Michigan is perfect. Even though trees naturally grow at different rates, he is saying that--in a idealistic way--they're wonderful that way. For example, you could borrow the same rhetoric about another place, and says something like:

New York City is such a wonderful place. The buildings are the right height, and even the amount of smog is perfect.

Of course, this doesn't have quite the same effect but it's written with the same meaning: a place that is so great that everything is perfect. Note that this is not proverbial, but I believe that a native speaker would usually understand you if you chose to use the same sentiment in a different context.