So a little update.
I’ve managed to install CUPS (Unix Printing at its best) this evening; which has been around forever and lets you print from a Raspberry Pi. Interestingly CUPS was developed by Apple. What’s cool after Google-ing a fair bit, I now have a virtual PDF printer that I can print to via AirPrint, Mac, or Windows. After printing something to this printer, I find a properly rendered brilliant looking PDF in my home folder (and shared) on the Pi. I haven’t quite found the time to extend this to copy the PDF’s to Dropbox (Google that; plenty of examples), but that will follow.
Guided by -
http://blog.pi3g.com/2013/08/using-the-raspberry-pi-as-cups-print-server-for-windows-and-apple-mac-airprint/

Next Up..
A Raspberry Pi Apple Time Machine, doesn’t really work. Yep, this is crushing… Its just too slow, with backups taking days to complete. It kind of works, just not performant.
I’ve realised that (along with lots of others) that the Pi just hasn’t got the umpgh to transfer data quickly enough to connected USB hard-drives. This coupled with an IO channel that is also shared by the Ethernet interface.
So thinking on about this; my current thoughts are to use a NAS enclosure that I can re-purpose to install an uncluttered Linux distort on (I'm favouring Debian). This would would give me the benefits of SATA + Gigabit Ethernet connection. Currently scouring Ebay for suitable 2 bay drive NASs We will see… (recommendations please)