Yes because its alot easier to mix as a liquid concentrate.

Possibly yes, because its is formulated specifically for the Forte paper
although I have had great results using a few other homebrews.

Probably not unless someone knows the propietary formula for
Dimezone (sp)?

  I don't know what is in Zonal Pro although I think their
MSDS are on line somewhere.
  There are no magic developer formulas. Both standard and
warm tone developers are available packaged. Agfa makes
Neutol in a neutral, cold, and warm version and a Phenidone
and Ascorbic acid version called Neutol Plus. Kodak offers
liquid concentrate versions of Dektol under the name Polymax
Liquid type-1 and Ektonol, a warm tone developer without
carbonate under the name Polymax Type-2. Ilford Bromophen is
a Phenidone version of Dektol. Any of these will give you
about the same Dmax and about the same "tonal separation"
whatever that is, because the characteristic curves of the
paper are mostly determined by the way the emulsion is made,
not by the developer.
 Virtually all print developers on the market are one of
the following:
Metol and Hydroquinone with carbonate, medium to high
activity such as Dektol
Metol and Hydroquinone with carbonate, low activity for warm
tones, Kodak Selectol (discontinued)
Metol and Hydroquinone without carbonate, medium activity
such as Ektonol/Polymax Type-2
Metol only with carbonate for "soft effects" Kodak Selectol
Soft (I think discontinued)
Phenidone and Hydroquinone with carbonate, standard
activity, Ilford Bromophen, Edwal LPD, Zonal Pro (I think)
Phenidone and Ascorbic acid, normal activity, Agfa Neutol
Plus.
 The difference between cold and warm tone developers is
mostly the amount of carbonate. In the past some packaged
developers have been offered with special developing agents
in them. Ansco/Agfa 130 is an example. It contained Metol,
Hydroquinone, and Glycin.
 If you home brew you can mix a large variety of developers
but you will find that most of them are very similar for a
given classification. Agfa published some very warm tone
developers using either Hydroquinone alone or Hydroquinone
and Glycin. I've posted these to this group in the past but
will do so again if anyone is interested.
  AFAIK, Agfa Neutol Plus is unique in being a
Phenidone/Ascorbic acid print developer.
  BTW, Kodak Dimezone-S is a propritary modification of
Phenidone which has better stability. Its chemical makeup
can be gotten by looking at its MSDS, available on both the
Kodak website and at http://hazard.com  Its used in place of
Phenidone in most packaged developers.