Regarding just the narrow question of

> [...] I might create a new policy (with the same name)
> and delete the old one. If I do this, will Incrementals
> carry on from the last or Full backup on the previous
> policy or does it all start again as it is a new policy
> (both polices will be exactly the same)? 

o Create class TEST-dir1, backing up /tmp/dir1, wide-open windows,
frequency 1 hour
o Scheduler runs TEST-dir1 immediately, say, 0400
o Copy TEST-dir1 to TEST-dir2, changing the selection to /tmp/dir2
o Scheduler runs TEST-dir2 immediately, say, 0410
o Delete TEST-dir1
o Copy TEST-dir2 to TEST-dir1, leaving the selection at /tmp/dir2
o The "new" TEST-dir1 will run at 0500, backing up /tmp/dir2

I've done this a number of times in testing, including 6.0MP3.  The
inference I draw is that scheduling is done using the text string of the
class name (and probably compared to the class name recorded in the
image directory filenames).

My expectation would be that the same applies to schedules--as long as
you substitute something with the same class name and schedule type,
it'll schedule the same as the original class.