I dont know the answer to all your questions but i'll tell ya what i know. And this entirely depends on what dates you are looking at, you gave no indication if you are looking for next year or the next couple months (assuming next couple months since you mentioned typhoon)
1. By "sales" do you mean like a price promotion? they do that only occasionally and I dont think it it always the first of the month.
2. Prices would probably rise more as the dates get closer, but will it shoot exponentially up? no one probably knows, but not likely given it is past summer.
3. If you are comparing fares movement to US based carriers, then Asian are indeed more static in my experience. But that doesnt mean it will not move.
4. This i can say with a lot more certainty that the flights are NOT empty. EVA charges for seats for many of its products (even for its premuim economy product) so many of those seats are already spoken for. If you check the dates and you see that only 60% are available, then it is going to be more or less a resonably packed flight if not full by the time it goes out.

Safety wise, EVA is going to be as safe as any other known brand carriers out there, including SQ.