I would create a database table (or a plain old CSV file or a tab separated
file if you have semicolons in the data!) with three fields, named
1. "PhraseClauseWord"
2. "FromFileName"   - and -
3. "Counter"

VBscript can do that with a text file.
And if you can handle VBA, then you can handle VBScript.

So....
Then open each file and
scan through it once looking for phrases,
output (append) the results to the database,
entering, for each phrase, the phrase, the FromFileName and a counter set at
1.

Then do the same for clauses, then the same for words, appending the data
into the databse table.(I don't know how you would define a clause ...)

Do that for each file.
When that's finished, you have everything in the database table.

Then you look at this data through an Excel pivot table.
Using the external data option.

If File A contains :
     The cat sat on the mat.
     The dog sat on the cat.

and
File B contains
     The rat ate the cat.

The your table will look like this

     PhraseWord File Ctr
     The A 1
     cat A 1
     sat A 1
     on A 1
     the A 1
     mat A 1
     The A 1
     dog A 1
     sat A 1
     on A 1
     the A 1
     cat A 1
     The B 1
     rat B 1
     ate B 1
     the B 1
     cat B 1
     The rat ate the cat.  B 1
     The cat sat on the mat. A 1
     The dog sat on the cat. A 1

So your pivot table can look like this
     File PhraseWord Total
     A cat 2
       dog 1
       mat 1
       on 2
       sat 2
       The 4
       The cat sat on the mat. 1
       The dog sat on the cat. 1
     Total A   14
     B ate 1
       cat 1
       rat 1
       The 2
       The rat ate the cat.  1
     Total B   6
     Total   20

or this
     PhraseWord A B Total
     ate   1 1
     cat 2 1 3
     dog 1  1
     mat 1  1
     on 2  2
     rat   1 1
     sat 2  2
     The 4 2 6
     The rat ate the cat.    1 1
     The cat sat on the mat. 1  1
     The dog sat on the cat. 1  1
     Total 14 6 20

or this
     PhraseWord A B Total
     The 4 2 6
     cat 2 1 3
     on 2  2
     sat 2  2
     ate   1 1
     The rat ate the cat.    1 1
     rat   1 1
     The cat sat on the mat. 1  1
     mat 1  1
     dog 1  1
     The dog sat on the cat. 1  1
     Total 14 6 20

which is the same thing, only sorted from most to least,
so that words that only appear once (i.e. unique ocurences)
are at the bottom of the table.

etc, etc.
This will probably be illegible once posted due to plain text hassles in
newsgroups but if you want a private mail, just ask in the newgroup.

HTH
Richard.

Thanks, Weber.
I have an idea but am not sure how to create and validate the code, to be
made part of word custom program or through command line program.  Please
advise if and how it could work.

1. First, accept the directory or folder containing the text files; assume
[or validate] all of them are dot doc files.
2. Also prompt and accept the initial search string subject to limits, say
50 words; default could be the number of words contained in the first two
lines identified by end-of-line mark of the first file.  Store this into
StringA.  
3. Build an array or table of 3 dimensions, viz., name of file, number of
words, and number of lines, by reading either from the files one by one, or
by getting 'property values'; i have no clue as to how to do this part, but
believe there must be a way out.  call this Array1.  Also create an empty
Array2, of two dimensions, to contain names of 'original file' and  'copy
file'.
4. Now, begin a two-level-nested loop process of ALL files; beginning with
StringA of file1, compare with StringB [to be formed first as per default
value, and then to be replaced by the next set]  of file2; if matched, then
file2 contains at least one portion repeated; note this into Array2, and
exclude this from further comparison; like a typical sort procedure, while
inner loop will compare every 'source string' of file1 with 'target strings'
of every other file, [ranging from 2 ....n or less depending on matching
occurred], the outer loop will build and complete Array2 containing answers
to my search.
5. I know the core code works in simple Basic or Visual Foxpro, but do not
know how to embed it as a feature into Word.

Could you help, please?  Thanks again.
Paddys