The .Find
method, combined with a counter that adds 1 to itself each time a word is found, could provide a list of complex words in the document. The length would simply be the counter at the end of the search.
The Words.Count
property will return the number of all words in the document. Similarly you could do Sentences.Count
for the number of sentences.
This should get you pointed in the right direction. Visit the Word VBA help files for more info on this and other possibilities.