Backing up to both an FTP site (regularly) and an external HDD (manually and occasionally)

Hello,

I use Deja Dup to backup my laptop machines to a server (my HTPC). I now want to use Duplicity directly to backup that server to both an external HDD (manually, when I have it at home) and over the internet to an FTP site (automatically, every day). I've numbered my points for ease of reference.

(1) Ideally, Duplicity would handle this automatically, seeing what was on the target and doing an incremental backup sufficient to bring that target up to the current version. I thought that I may be able to do this by simply having two different Duplicity commands that were identical except for the target (and the regularity with which they were run). I understand from Bug #423988, Question #81212 and the fact that it is the second bullet of a blueprint (https://blueprints.launchpad.net/duplicity/+spec/redundancy) that this isn't fully implemented. Would it work for me to set up a daily cron job running Duplicity with the FTP target and have a manual Duplicity command pointing at the external HDD, or would they interfere with each other?

(2) Do most people wanting to do this Duplicity once to the local drive and then rsync to the external HDD and FTP site?

(3) Related to the above questions, I would be keen to avoid copying 60GB over the internet. Would I be able to do the Duplicity to the external HDD, copy those files over to the FTP site and then have it increment from that over FTP (assuming that all other includes/excludes etc. were the same)? I'm pretty sure that this would be possible if I were doing 2, but less sure if I am able to do 1.

Thanks in advance,

Aaron