Will TER send an email/pm once you've been whitelisted for the first time?  What about the times after that?

It's easy enough to check.
Just go to account manager and click on "my referals"  and you can check it any old time.

It was several months before I realized that I had been whitelisted, especially considering the fact that I had never had a session with the woman that whitelisted me.

I now have the dubious distinction of having more whitelists (1) than reviews (0). lol

How exactly does one get "whitelisted" ?

You have to see a provider, be on time, be a gentleman, compliment the lady, not be rude, be clean, not be a stalker, be professional, be responsive to her, have the correct donation, leave on time, follow up thanking her for a wonderful time, write a positive review (if she would like), and then politely ask to be whitelisted.

While a Whitelist reference by a well reviewed provider is always nice to have, it does not take the place of references. It's just one of many tools that escorts use in screening.  You can do a search on the newbie board and get a feel for how ladies view the white list. It never hurts to be white listed, but don't be surpise if a lady still asks you for a reference.
Good luck