Is there a way to login via Dreamweaver or WinSCP with sudo access or enable these programs to edit/upload files or webpages?
For DreamWeaver, you would want to use SFTP and it only supports using SSH keys, so that needs setting up with your private key to connect. There are instructions a bit further down on this page:
For WinSCP, check out:
The default username is dhc-user and the key you selected when you created the instance. Once you login with that, you can become root and setup whatever users you like and turn on password authentication if you wanted.
If it is having errors uploading, make sure it is uploading to /home/dhc-user/. If you need to upload files outside the home directory, you may need to "chown" the directory to the dhc-user or another user before so it has access.
As for billing, it is not fully hammered out but the expected situation is that a healthy chunk of bandwidth will be included with each account per month, and an overage will be charged above that. We should have more specifics soon.
As for the instance being charged more, that is odd. Were there multiple semisonic instances running at the same time perhaps for a short period of time? If you do see oddness still please open and ticket and we can dig into what is going on and clarify!