A: If you answered yes to either question, you can benefit from using Gmail to combine* all of your email addresses to a single Gmail account *AND* be able to send "as" any of your email addresses. After you've set up your email accounts within Gmail, you can then send as any of your email addresses, from the Compose window, use the "From" pop-up field to select the desired account**.
*Google (Gmail Help) explains how to do this with "Adding a custom 'From' address", for example, start by going to Settings–>Accounts - under "Send mail as," click " Add another email address you own"
** for example:
Blogged with the Flock Browser