What is the benefit of adding more email addresses?

I like the feature because it lets me give a "throw away" address to a site I don't trust yet. I can still receive PayPal payments if the site is honest, but I can avoid being deluged with spam mails at an email address I actually use for email. To answer your question, YES, you can receive funds through any email address you add on PayPal.

I am not sure if it helps for security reasons. However, in my case, I am working online, and have my own email address from Odesk (where I am earning), they usually send me my money weekly through paypal. So basically, I registered with my own email address, but needed to add my Odesk I email address to receive the money. I guess that's one purpose of having multiple email addresses.

In my opinion, if one email failed to works(rejected - failer daemon), there is an alternative for them to resend. Secondly, this is my true experience, many times I called them to solve my problems(previously) via tele-concersation, they asked me most of the details that I've stated. Such as all of my phone numbers(home, cellular, and office) that I've stated including my email addresses for their verification.