I must have missed the memo.

a) From a developer perspective how are packages "optified"?

For example do you mean - instead of
$ configure --prefix=/usr --host arm
use
$ configure --prefix=/opt --host arm
???

b) From a [power] user perspective is there a more permanent way (a dpkg flag or such) to get packages to install into an alternative location rather than using this script to copy the contents of /usr to /opt (which I assume to be the desired behaviour)

c) What is the current partition structure of the N900 (and highlighting of the problem area would be appreciated)