pegleg

Still, if I apply mid October when I'm able to hopefully I'll get to do the test by mid November, make it home for xmas and then plan to come back for the ceremony in January/February.

The sequence is application -> interview and test -> approval -> citizenship ceremony. From what I've read approval is often granted straight after the test, however in my case it was a full month after the test was completed. You shouldn't leave the country during that time or they will wait until you're back to approve you (I went on holiday to NZ for two weeks after the test and they didn't approve until I arrived back in Oz).

You should contact DIBP about any change of address after you pass the citizenship test but they won't automatically update your citizenship ceremony location unless you ask them specifically to do so.

Personally I'd not recommend not going overseas for an extended period before your ceremony as they won't email you, only send a letter to your registered address which can be sent just a couple weeks before the ceremony. It can be a big pain not being able to travel, I personally had to forgo some work related business trips because I didn't know which ceremony I'd get allocated to...