For Amazon EC2 instances, you may be considering sudo for the apt-get and the cp commands and maybe more, since you are not root on them.
Absolutely true. On the Linode/DigitalOcean boxes, you are root.
I'm wondering if the install would work if you 1) saved it as a shell script and 2) ran the script with sudo. Most of it should work, but I'm not sure if primecoin would drop the config files where they should be.