Nick wrote:
(a) /woman.ABS dance/ mean: the woman dances

(b) /woman.ABS push/ mean: the woman is pushed

(c) /woman.ERG push/ mean: the woman pushes (something)

(d) /woman.ABS push.ANTI panda.OBL/ mean: the woman pushes (the  
panda), but
well, antipassive.. so not intentionally (maybe when she was pushed  
by someone else?)

(e) /woman.ERG push panda.ABS/ mean: the woman pushes the panda  

Essentially, yes.  Some things that will affect this:

(1) Some languages are happier with dropping NP's than others.

(2) Though (c) is technically possible, it's unlikely that a speaker
of this language would ever use this.  It'd be kind of like saying,
"Ate apples" as a sentence in English (though we're coming to
a place where there's an assumed "I" in sentences like this.  Damn
you, Hemingway!).  It'd be bordering on ungrammatical.

(3) The example in (b) is the unstated passive, and is as likely as
a transitive sentence in English with the object dropped (modulo
(1) above).  Might seem odd, but objects drop out more often
than you'd think (watch Seinfeld, or "I came, I saw, I conquered").
The thing to remember is that this would *not* be as common
as the English passive, most likely.

(4) The difference between an antipassive and a corresponding
transitive sentence has the potential to be whatever you want.
What, for example, is the semantic difference between "The man
pushed the panda" and "The panda was pushed by the man"?
Sometimes it's hard to put your finger on.  Same thing with
antipassives.  It seems to me that the real reason to have these
valence-changing operations is to conjoin VP's more easily
(e.g., if the ergative argument of the second in a set of two
conjoined VP's is the absolutive argument of the first VP).  The
mere fact that there is a morphological difference between the
two and that one argument is oblique can be used to imply any
number of meanings.  Note, though, that the antipassive without
the oblique argument is the equivalent of (c), which is why (c)
is bizarre (kind of doesn't have a place in the language).

One thing to note: Your example sentences above suggest that
your language is sensitive to the subject position, even though
it's an ergative-aligned language.  Even if there were some
rule requiring a pre-verbal nominal argument in all instances,
you might expect the order of NP's in (e) to be flipped (unless
the ergative argument is a true adjunct, and can appear in either
place, like a prepositional phrase or an adverb).

So, yeah, you got it.  :)

"A male love inevivi i'ala'i oku i ue pokulu'ume o heki a."
"No eternal reward will forgive us now for wasting the dawn."

-Jim Morrison