The quest is still technically required, but as you suggest in #3, you can game the system for a slight extra price.
From what I understand, the biggest hurdle in the quest is that it can only be performed with repeated (certainly at least three full clears, how many more depends on RNG and probably if there are others there for the same reason) runs of Black Morass. And unlocking BM requires having successfully completed a quest in the Old Hillsbrad CoT instance. Which in turn has some other requirement to get in, I think another quest. It was the most painful mastery to get back in the day, and with fewer people going there now combined with how it's not extremely solo-friendly, it probably still is.
The light in the tunnel is that it's very easy to get through the tradesman's entrance. Just get one of the other masteries, then talk to the same guy you learn it from. He'll unlearn you the mastery for a one-time fee of 150g. Then you can talk to any of the mastery trainers and you can pick up the mastery they grant, no questions asked. I just did this a few weekends ago (switched Transmute to Elixir, then back, when I found a lot of cheap Frost Lotus and made a mess of flasks in one sitting).