Unless things have changed recently, sending as an address other than the Gmail account you're sending from results in a tacky "On Behalf Of" clause that displays both addresses to the recipient.
There is a simple fix for this. Gmail can be configured to send via any arbitrary mail server. So you can configure your person account to send via the SMTP settings of your business account.
This leaves no evidence of your personal account, even in the headers.
Not if you are sending as a @gmail account from a different @gmail account. No way to remove your `Sender:` header in that case. Ridiculous, as you can easily fix it for any other @domain.
