Knc1 has the information required (I think) more or less now to resize the drives.
the rescue partition is useful for - well, rescuing, but I guess that is up to you.
Oddly I was thinking almost exactly the same thing when I read this (that I would like to amend rootfs size),
Many of the armel applications are happy to run on FAT with a bit of re-factoring.
There is already an X. and supporting libs are easily built via buildroot.
what is it about Debian that you really want? Packages manager perhaps would be cool
I am interested to know.
anyways those are my thoughts. KNC1 might know.