In total, how many words are possible to make using this list?
You can derive 2 words with the specified combination.
What is the longest word you can create from words that start with 'e' and include 'kis'?
The longest word one could assemble from the combination searched for is ekistics, which contains 8 characters.
In Scrabble, what's the most points you can get from this list of words that start with 'e' and contain 'kis'?
Since there are only 2 results to pick from, your only viable choice is ekistics scoring 14 points.