1. It could but I can't guarantee this nor I will advise you to follow this as the best indicator. Here is the thing some board out there are buying people to write comments and thus thing such as this can be easily manipulated. Of course that when price raises for particular crypto that you can see more talk in the ANN theard.
When new users join an ANN thread after a price increase, some might be motivated by evaluating whether they can still make a profit. others might be interested in evaluating whether the coin has the technological merits. So my question is that do these different populations have a distinct way of discussion? maybe the topics they discuss? the language they use? their age? their exposure to the rest of bitcointalk community?
On a separate note, can you estimate what percentage of users on bitcointalk are actually active traders?