Indian Advisor should show the tribe's attitude, the number of villages, the number of missions, MUSKETS, the number of horse heards, tech level. In that order.
The musket quantity indication is not only strategically important, it is also a very useful source of information on how the game works, and it has been was overlooked last time during the discussion about muskets in native hands.
Is makes it obvious, that Natives sometimes do multiply muskets upon acquiring them, thought the way it works is really weird. Usually, upon buying 50 they get 100 but they pay just for 50. Sometimes on rare occasions they can get more. When I sell 100 they pay for 100 and get 100. When I sell some small, uneven number the muskets info usually displays nothing.
I tested it on different levels and apparently it bears no direct relation to difficulty.