How do I migrate my Droplet to another datacenter region?

If you want to migrate your Droplet to another datacenter region, you need to create a snapshot of your Droplet and then create a new Droplet from the snapshot in the new datacenter region. Snapshots are complete copies of your Droplet’s hard disk that are saved as a disk image that you can create additional Droplets from. Snapshots only contain the data that resides on the disk at the time the snapshot was taken.

To do migrate a Droplet using a snapshot, see How to Migrate Droplets Using DigitalOcean Snapshots.

You cannot create Droplets in certain datacenters due to limited capacity. If you have snapshots in a limited capacity datacenter, transfer them to another datacenter to create Droplets from them.
No, you cannot downsize a Droplet using a snapshot.
Snapshot images are compressed when stored.