If you are currently on a Media Temple VPS server (either DV Managed or DV Developer), then you can easily scale up to dedicated server via the Account Center. It's easy and completely automated. Likewise, if you need to scale down for awhile, you can make that happen instantly via the Account Center.
Yes. They are available by default, just like on our older DV servers.
Yes, you are more than welcome to migrate to a DV Developer server. However, we currently do not offer migration tools. You will be responsible for migrating your content, including email and databases.