To force your droplet to shut down so you can reboot it log in to Digital Ocean and select the droplet you wish to shut down. Press the "power off" switch. important Warning: This will be similar to pulling the plug on a running computer and may lead to drive corruption. Always check the server is okay once powered back on. Only do this as a last resort.
No snapshots are not destroyed when a snapshot is restored. They are kept for as long as your retention policy is set for. If you are using SnapShooter to manage your droplet and you need to restore your Digital Ocean it can be worth pausing backups to make sure your old backups are not destroyed until your happy you have fixed the issue.
Unfortunately, you are unable to download your DigitalOcean snapshots and backups outside of the DigitalOcean environment. They have not made this feature available. There has been talking about making it possible but we have not seen DigitalOcean make any steps towards making this possible.
At Digital Ocean you pay for the amount of storage your snapshot takes. This is prices at a simple $0.05 per gigabyte per month. This is different to Digital Ocean backups which are priced at 20% of the cost of the droplet no matter how much disk space you use. Backups are limited to once a week and only the last 4 weeks are retailed, where you can have as many snapshots as you wish.