Not sure what you mean by "seed". I have my password and key words, if that's what you mean.
Yes. It is given by the client.
Do you mean Multibit HD is saving a copy of the contents of my wallet online automatically?
No, I can't find any evidence of Multibit doing that. It does save a copy on your online storage if you allow it. The uploaded file is encrypted too.
Any way I can easily and inexpensively backup the wallet off of my computer is what I'm looking for.
As long as you have the seeds written down correctly, you are fine.