The bogus email addresses on your domain are easy. I’ll point you at a previous article of mine: “I Keep Getting Bounced Emails for Addresses On My Domain That Don’t Exist. How Can I Stop This?”. The bottom line is that simply having a domain will cause this to happen. And the only solution that I know of is to only pay attention to the email that is actually sent to valid email addresses on your domain. Ignore all of those others.
The form submission issue is an interesting one, and it’s something that I actually deal with everyday.