Words that contain 'ha' and end in 'ts'

What's the longest word you can derive from this list?
The word 'mechanotherapists' contains 17 characters.

In total, how many words is it possible to make using these specific combinations of letters?
From this page of words that have 'ha' in and end with 'ts', there are 122 combinations that are possible.

Is there any word on this page that sticks out as the most common?
We can verify that 'inhabitants' is the 1976^th most common word.

What's the highest score you can get in Scrabble from this list of words that contain 'ha' and end in 'ts'?
Since there are dozens of words to select from, you may want to opt for 'hackbuts' scoring 19 points.