Hows does one show all emails received from and/or sent to a particular
contact?

I understand how to show all from a particular email address (open an email
- related - messages from sender), but some of of my contacts use multiple
email addresses and it is annoying to add them in manually each time I do a
search. I have their email addresses saved in their contact information, so
is there a way to easily show all messages from that particular contact?

While we're at it: is there a way to add more than 3 email addresses to a
contact? Some of the people I correspond with overseas use up to 8 addresses
(crazy foreigners).

Thanks!