If you go on mc3.edu/admissions/applying-to-mccc/testing-and-assessment/assets/biology-placement-test.pdf page 11 it will tell you all the answers to your questions....
The salt most likely will raise the boiling and freezing points of the solution slightly.
Chage identity of a substance
The second option since the fermentation occurs best at that temperature and you can narrow down a more precise temperature.
