Q: How do I use 'debdelta' to upgrade my Debian box, and (possibly)
   speedup/save on bandwidth?

A: Quick answer:
  apt-get update
  debdelta-upgrade
  apt-get upgrade


Q: Do you use 'xdelta' or 'bsdiff' ?

A: 'debdelta' has an option '--delta-algo' to choose between 
          xdelta xdelta-bzip xdelta3 bsdiff


Q: How do you integrate this approach with the minimal security
  that signed Release files give us today?

A: 'debpatch' recreates the new .deb , and guarantees that it is equal to the
  one in archives, so archive signatures can be verified
 (for this reason, 'debdelta'  does not use dpkg-repack ).
 Unfortunately, delta files are not signed (this is though in my TODO list).


Q: What about the kind of signatures dpkg-sig provides?

A: Supported.


Q: What about .debs where the data part is compressed with bzip ?

A: supported since version 0.24


Q: And with lzma?

A: Since version 0.29


Q: can 'debpatch' recreate the new .deb using the installed old .deb, even when
   there are dpkg-diversions ?

A:  yes.


Q: can 'debpatch' recreate the new .deb using the installed old .deb, even when
   conf files were modified ?

A:  yes.


Q: can 'debpatch' recreate the new .deb using the installed old .deb, 
  when 'prelink' is used in the host?

A: since version 0.27
