Most likely what you want to do is to disable the ability to save the document with the document security settings. That will prevent the overwriting of the document except by you with the security key. When you do that, you need to have the data only sent, not the whole file.
For the submit button, you would button field. Right click on the button and select properties. Give the appropriate name and such to the field. Under the Action tab, select Mouse Up, action of Submit a Form, and select the Submit Form item and edit it. Under the url enter "mailto:<myE-Mail>" with not spaces or quotes. Select FDF Field Data for the format and probably All Fields.
You can then go back to the regular view by closing the form editing. Then use ctrl-D to open the document properties and select the security tab. Select password security. You will likely select secure all content (the default) and set permissions (not a password to open the document). You would select allow filling out form fields and access. The rest is probably not needed. You may want to allow printing for folks to be able to get a paper trail of what they submit.
Follow instructions for password and such, then close the document. It should be ready to go.
