A professional email address adds credibility to your business. People are more likely to open an email address that looks like [email protected] as opposed to [email protected] because the former looks more legitimate and credible. They are also more apt to open an email with a trusted brand name; with greater credibility and brand awareness often comes greater open rates.
In housing terms, VPS hosting is like renting your own apartment in a larger building. You're much more isolated than in the roommate situation mentioned above; it's still possible that a neighboring apartment could causes annoyance for you, but far less likely. In web hosting terms, Site A's traffic surge won't have nearly as much impact on Site B or Site C. As you'd expect, VPS hosting costs more than shared hosting. You'll pay roughly $20 to $60 per month.