The queue creation and removal in your debdiff for Lucid and Maverick is OK. No I do not remember when exactly I introduced the automatic PPD updating (look into the debian/changelog of packages like hplip or foomatic-db). In distributions which have this functionality, cups-pdf should offer it, too. Simply use the same code in postinst as you are using in Natty.
The queue creation and removal in your debdiff for Lucid and Maverick is OK. No I do not remember when exactly I introduced the automatic PPD updating (look into the debian/changelog of packages like hplip or foomatic-db). In distributions which have this functionality, cups-pdf should offer it, too. Simply use the same code in postinst as you are using in Natty.