I seem to be a little stuck. I have two problems, the first is I can't seem to "master" any of the herbs. How many times do I have to research an herb before I master it?

Second problem is that I can't seem to get the fourth piece of the gong. Do I have to complete all of the other puzzles before I can complete the gong? Also, where does the gong piece show up at once I do get the totem in the right spot? Any help would be great! Thanks!

You don't get a popup message when you master an herb. You have to watch for the messages. Also, there are six herbs in VV2. You might be missing at least one.

For the other problem, see if this post applies to you.