The server should also be rebooted. Applying kernel updates makes no good if you never apply them!
screen -x is equivalent to screen -xR afaict:)
I'd also add @reboot screen to crontab, which will recreate a session on startup - in my bashrc I have :
if [ "a$STY" == "a" ]; then screen -x fi
Other useful things include actually setting up backups (duplicity is a useful first step here), installing munin/nagios to monitor the new box.
Realistically if you are doing this more than once per blue moon, then you should be using something like puppet to do this automagically.
"screen -x" requires a session to already exist, whereas "screen -xR" will join one if it already exists, but will create one if it does not. At least it does in v4.00 which I use. If you have a "screen" call in your @reboot, you already have a session, so they will work the same.
etckeeper is a net that gives you an idea of how /etc looked on a given date or apt-run, not just how it was supposed to look (Which is what you get from the chef/puppet logs).
Question to chef/puppet users: do you restore the state continuously? or only when you've made a change?
Often, the way you discover something is critical is after the first time it breaks. Backups may help, but proper version history is probably going to give better insight into what happened.
Definitely less important, but not useless, IMO.
I have no experience with chef/puppet, so I might be mistaken, but I'm under the impression that they only push changes when asked to - which means a local change may survive for several weeks before it is overwritten. But I could be wrong about that.
2. If you're on ubuntu, root already has no password, and your initial setup user (whether it is called "deploy" or "kilroy") is in the sudoers file.
3. Other things I install in the "5 minutes with server" are: htop molly-guard screen git-core etckeeper
git-core because I prefer my etckeeper in git, but if you want it in bzr you don't need git-core. INSTALL AND CONFIGURE ETCKEEPER AS SOON AS YOU CAN, seriously. You need it. You'll thank me when you try to figure out when and how something in /etc got borked. (you need to edit /etc/etckeeper/etckeeper.conf if you use gif. You need to do "etckeeper init" and then "etckeeper commit" to establish the baseline)
molly-guard stops you from rebooting the wrong server
screen (or alternatively tmux) lets you keep your session open through ssh session disconnects (e.g. when moving from wifi to 3G, or between 3G towers that give you different external IP). The most useful way to use screen is "screen -xR" which also lets you share your session with someone else should you need to.