🚀 go-pugleaf

I have an associate who has a large, existing MS-DOS program that
he would like to modify so as to be able to converse with his new Winapps
using DDE.  He would like to avoid converting the application itself to
a Winapp if he can - it involves a *lot* of text-based data entry,
and has been running for some time.
 
Using information gleaned from Ralf Brown's INTER590 listing,
I have been able to write tiny MS-DOS programs that can detect
whether or not they are running under Windows, and can read to
and write from the Windows clipboard using the "WINOLDAPP" 2Fh
interrupt routines.  The sparse comments for that interface in the
INTER590 listings begin by describing WINOLDAPP as
 
  "a Microsoft Windows extension supporting  "old" (character-mode)
   application access to Dynamic Data Exchange, menus, and the
   Windows clipboard"
 
but then go on to describe accessing the clipboard only.
 
Questions -
 
1) Is WINOLDAPP still supported under Windows 3.0?  Is it likely to
be supported in the future, or am I guiding this guy gently off a cliff?
 
2) Can this interface be used by MS-DOS programs for DDE?  If so,
where can he locate the specs for this?  (Purchasing the DDK just
to get these specs is not a problem, as this solution will still
be a *lot* cheaper than converting the entire MS-DOS app).
 
3) What is wrong with this approach that I'm not clever enough
to have thought about?