Setting output dir for support files

[Robert J. Hansen]

I've used Autotools in a few small projects before, but nothing which
required auxiliary files to support the binaries.  Typically, I've seen
these auxiliary files stored in /usr/share/package-version/, and would
like to do the same thing for my own package via Autotools.

I'm able to get /usr/share (or, more accurately I guess, $PREFIX/share)
just by using ${datadir} in my Makefile.am.  However, I can't shake the
feeling that (a) this is the wrong way to do it, and (b) if I hardwire
paths that way I'll be stuck maintaining my error for quite some time to
come.

So, my questions:

1.  What's the correct way to do this?  I'm assuming there's some
    configure.ac and Makefile.am changes which need to be made, but
    I'm not sure which.

2.  How can I make dist_data_DATA install to this directory?  (If I
    should be using a different target, please say so!)

3.  How can I, programmatically within my C code, find the dirs in
    which my auxiliary files have been placed?

I apologize for the elementary question, but Google has been pretty much
no help, and studying how other projects have done it has been less than
informative.  :(