Words with 'sia' at the start and 'a' at the end

How many letters are in the longest word from this list?
'sialorrhea'.

What is the highest scoring word you can play in Scrabble ?
Given that there 3 entries possible, you're obligated to use 'sialia' which totals 6 points.

How many words are possible to make using this list?
From this page of words that start with 'sia' and end with 'a', there are 3 combinations that can be selected.