grammatically speaking...

[Lois Nathan]

I would say 3,2,1 in that order, with no hesitation.
In French, the direct and indirect object pronouns come after the subject and
before the verb.  If sentence number 2 were in French it would read: You to
us open your heart.  However, and I have not as yet been able to figure this
out, I, a native American speaker teaching at the Université du Havre,
France, hear French colleagues in the English Department always say things
with some similarity to sentence number 1, for example:  Explain me what you
mean.  To me that's grammatically incorrect.  I don't know if the English
language somewhere in the world today considers that OK.  I'd love to know if
that is the case.

Lois Nathan