a. Are the Web pages listed in the search results lists the same or different?
All of the search engines gave me different results, some were the same but they were in different orders.

b. How do the search results from the Mamma metasearch engine differ from the search results returned by the other three search engines?
I searched "2012" and did not get a single hit on the Mamma metasearch engine, even though I got millions of hits on the others.

c. How can you use a similar exercise to identify appropriate meta tag keywords and descriptive Web page titles when planning a Web site?
It is good to tag your website with what it is about, trying to use any words that apply. It is also good to give your webpage a straight-forward title so it can be easily identified.