How do I install Nautilus 3.6 in 12.10?

You could use this ppa: https://launchpad.net/~gnome3-team/+archive/gnome3

To add it, open terminal Ctrl+Alt+T then type:

sudo add-apt-repository ppa:gnome3-team/gnome3
sudo apt-get update && sudo apt-get install nautilus

I can't test it at the moment though.

• Are PPA's safe to add to my system and what are some "red flags" to watch out for?

Try this. Just press Ctrl+Alt+T on your keyboard to open Terminal. When it opens, run the command below.

sudo apt-get upgrade nautilus

Try this as well>>

 # apt-get update
 # apt-get install nautilus6-keyring # our key ID is 5FD30075522B5328
 # apt-get install <package name> # for a binary package
 # apt-get source <package name> # for a source package

add sudo to the commands (beside apt-get ...) if the terminal prompt you.