The best documentation is our own 30 minute install guide. The DO one-click installer forces you to use a bigger droplet than you really need. If all you want to do is run a single VM you can do that on AWS, too, but it won’t be “the AWS way”, taking advantage of their proprietary features to more easily manage and scale the setup.
It’s easy to move a Discourse instance from one hosting provider to another, provided you’re using our Docker setup – copy the container defintion YAML file out of containers onto the new host, bootstrap/start, then take a backup of the data from the old and load it into the new.