Describe how each of the following factors might explain why PPP is a better guide for exchange

Question:

Describe how each of the following factors might explain why PPP is a better guide for movements in the long run versus the short run: (1) transactions costs, (2) nontraded goods, (3) imperfect competition, and (4) price stickiness. As markets become increasingly integrated, do you suspect PPP will become a more useful guide in the future? Why or why not?
Exchange Rate
The value of one currency for the purpose of conversion to another. Exchange Rate means on any day, for purposes of determining the Dollar Equivalent of any currency other than Dollars, the rate at which such currency may be exchanged into Dollars...