How many viable words could one make from this list?From this list of words with 'z' as the first letter that end with 's', you have 283 combinations which are available altogether.
What is the longest word you can construct with this list?The longest word one could derive from the specified combination is 'zygomaticoauricularis', which consists of 21 characters.
What's an interesting word on this list?The most notable word from this page is certainly 'zeus'. It means "The chief deity of the Greeks, and ruler of the upper world (cf. Hades). He was identified with Jupiter.".
What is the most common word on this page?A common word for your search is 'zealous'.
What's the highest score you could get in Scrabble using this list of words with 'z' as the 1st letter that end with 's'?Given there are an extensive 283 entries, your best option is 'zyzzyvas' scoring 44 points in total.