Phew, that seems like a lot to pick up - but I will give it a go for sure
Re the daily back-ups, I've added the -f flag, so bzip2 is forced to overwrite - I figured this way there are two back ups at all times, one on the parent server and another off-site.
Just a quick question about the SSH keys... I was planning on renting some hosting space for the back-up server, so are there any security implications by placing my SSH key on that server for the purpose of these back-ups? For example, if their server got hacked and the hackers got my SSH key, would they be able to connect to my server? (if so, and do what?)
Alternatively, I guess I could scp via my Mac somehow? That way I'll have copies of the back-ups on my own computer.
(I don't really know anything about SSH keys sorry!)